（Xibalba Studios首席游戏设计师Rafael Vázquez针对开发者难以评估游戏实际难度的问题，设计了一种考察游戏难度的方法，并以三款横向卷轴动作游戏为例进行说明。）
Ʃn=0 = (ETn)(ESn)
*Ʃn=0 = (Etn)(ESn)将敌人威胁指数与情况乘数相乘，并将每批敌军危害性的结果相加。
这三款游戏分别是《合金弹头》（由SNK于1996年发行的街机游戏）、《闪克》（由Klei Entertainment于2010年开发，本测试采用的是其PC版游戏）以及《铁血兵团：反叛》（由Arc System Works于2011年开发的Xbox Live Arcade和PSN游戏）。
提示：如果想直接衡量游戏进程的速度，可以参考Ben Cousins计算玩家行动的方法。他在《Elementary Game Design》一文中描述了这种方法，你可以通过其个人网站www.bencousins.com了解详细内容。
在这个环节将近尾声时，玩家又迎来了一个高峰，遭遇其他坦克的攻击。如果玩家的Metal Slug此时的战斗力尚存，那就无需担忧这个问题，但如果Metal Slug在对付直升机时就已经成了炮灰，那就要做好心理准备了。不过游戏此时会增加玩家坦克的健康值（绿色垂直线），以免玩家在遭遇这些敌军坦克时挂掉。
前不久，我们把免费模式的这种设定简单地抽象为（虽然不同的游戏可能在进程上稍微有差异，但整体的设定节奏基本都在这个范畴之内）：玩家在（一般情况下都是单机线阶段）level a所向披靡（毫无疑问所有的游戏设定指数方面，玩家都能够满分完成，成就感爆棚），在level b稍微遇到阻力（基本没有完成的相关难度，只是适当提升了系统npc的数量和数值，当然也可能优化了npc的智能程度），在level c如果不小心就会受挫（这个阶段的玩家整体战斗数值比如攻击性、防御性、技能和可携带的随身道具，与系统给关卡设定的通关数值相当，获胜或者失败已经存在概率了），在level d即使全力以赴也经常挑战不了npc（这个阶段的玩家数值已经全面劣于关卡系统的挑战数值，npc不管在数量上、技能上、智能方面都全面领先于玩家当前的最大值，受挫度十足）。
让我们以近期发布的游戏《Dead Money》为例，这是《辐射：新维加斯》的最新可下载内容。游戏受到了玩家和媒体的攻击，他们认为其难度曲线并不合理。在《Dead Money》中，奴隶凌驾于《辐射》系列作品原本无尽的自由之上，玩家被爆炸物驱赶到某个非常特别而且几乎是线性的路径中，如果玩家过于深入人迹罕至的地区，就会不断遭到伤害。游戏中的许多挑战是摧毁不断播放爆炸声波的广播发射机，而这些东西通常隐藏在桌下、壁橱中和许多难以企及的地方。如此设计的目标在于为玩家创造出某种紧张感，玩家需要在自己被炸弹炸死之前迅速找到广播发射机。
但是，《Dead Money》的问题并不在于机制本身。从基本层面进行分析，游戏的任务仅仅是玩家同时间赛跑，去移除环境中的威胁，即在角色被炸死之前关闭开关。就故事线路而言，爆炸循环机制固然很有效，但是本可以被许多相似的机制所替代，而且能够发挥同样的效能。更为重要的是，替换之后就不会像这样让玩家产生挫败感。比如，辐射和毒素威胁在《辐射》的世界中极为常见，那么，为何Obsidian不选择使用辐射的形式在表达同样的威胁呢？有趣的是，这种解决方式确实有在《Dead Money》中使用，但是使用的次数很少。用功能相似但较符合《辐射》设计方式的游戏机制来替代爆炸，我想抱怨游戏难度的人就会少得多，因为在这种情况下，玩家会认为挑战与《辐射》的游戏世界契合度更高，而且从整体上来说限制性更小。
篇目1，How Tough Is Your Game? Creating Difficulty Graphs
by Rafael Vázquez
[Having trouble figuring out how difficult your game really is? Xibalba Studios lead game designer Rafael Vázquez devises a method for plotting difficulty -- and uses three popular sidescrolling action games to test the theory, in the process explaining how difficulty meshes their overall design.]
A few months ago, during the prototype stage for a new project, I noticed a problem starting to brew. We were having lots of trouble identifying the ideal difficulty for our game, as different members of the team had very different ideas on what is the perfect challenge.
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I know this is a common issue for small, diverse teams, as what one member might think is a walk in the park another will find more akin to torture. The problem was that everyone had different skill levels, and because of this we weren’t going to reach an agreement anytime soon.
After thinking about this issue for some time, it came to me that difficulty in a game should not be related to player skill, but to the game itself. Instead of looking at the game’s difficulty as a static, all-encompassing threshold, we would do better to discuss how it changes throughout the game.
With this in mind, I tried to develop a method to measure and compare how challenge rises and falls across a game, independent of the player’s skill. This article tries to explain this method. It might still be a little rough around the edges, but I believe it’s a good start, and I hope it encourages discussion in the community so the method can be perfected.
Enter Difficulty Graphs
Getting difficulty right is tough. It might seem redundant, but that doesn’t make it any less true. Make the game too difficult, and people will get frustrated; make it too easy, and they get bored. This is common knowledge, and so designers typically strive for the middle ground. Most of the time, we do this by gut feeling, which is fine.
As it is, the game’s difficulty really depends on the type of game and the type of response we want to get out of the player. A calming social game and an adrenaline-pumping FPS are worlds apart in challenge. The problem comes when you try to talk about this challenge to your fellow team. Long hours pass, and no one seems to agree if that game section is just the right amount of tough.
This is because difficulty is subjective; it depends a great deal on an individual’s skill. To make things worse, the right difficulty also depends on what each person finds fun; some people like masocore games like Super Meat Boy. So when you’re trying to create a game, it’s a real problem to find common ground from where to start discussing.
There is a solution, however — a method to find a common base which we can all agree on: difficulty graphs. Before we dive in though, a quick disclaimer. This method is not for creating difficulty (that’s still up to the designer’s gut, I’m afraid), but for difficulty analysis, and as a means to start meaningful conversation with the rest of your team about it. These graphs don’t show you how a difficult a game should be — only how difficult it is.
So What Are They?
They are graphical representations of how difficulty changes throughout the game. This is to say that they plot how challenge changes over time. There are two main types, time-based and distance-based. The first places the spikes in challenge according to the time spent played (taking away paused time and death); while the second places them depending on where the challenges appear (assuming a direct route from start to goal).
Both have their advantages, and some work best depending on which type of game you’re testing. For arcade games like Asteroids or Geometry Wars, time-based is really the only way to go, as there is no real displacement towards a goal.
On the other hand, most FPS use location-based triggers for their enemies, so distance-based graphs work very well. Personally, I like time-based graphs better, and we’ll get to why in a moment.
Nitpickers might have already noticed that both of these still depend on the player. How fast the player goes through a level and how much time it takes him to get from one challenge to the other depends on how good he is at the game, and also at his play style (if he likes exploring, you can kiss time-based graphs goodbye).
The truth is that our medium is experienced differently by each and every one of us, and this is something we have to live with. The best we can do is get data from multiple playthroughs from different people and average them out. As a matter of fact, difficulty curves can only be applied after playtesting the game several times. After enough testers have tried the game, you’ll get a pretty good idea of what the average player experience is.
As you might recall, difficulty is subjective, and asking all the testers if they felt the game too difficult might give you wildly different answers (you should still do it, though). How then can we measure a game’s difficulty if it depends on the eye of the beholder? The trick is we compare it onto itself.
Say we have a basic enemy that deals x amount of damage. Let’s say he has a threat level of 1; this will be our base enemy. The threat level is basically how difficult an enemy is compared to the player. If, on the other hand, we have another enemy with twice the amount of firepower but the same in all other aspects, we can go ahead and say that it is twice as dangerous and give him a threat level of 2.
I know this might seem to oversimplify things, and that other factors like location, position, and the presence of other enemies matter… We’ll get there. The point is that, by taking the easiest challenge present as a standard (your base enemy), and comparing it with other challenges in the game we can quantify how tough each one is independent of skill. No matter how good you are, an enemy that is three times faster is tougher than the standard.
So, let’s recap the steps:
* First, you have to determine what the game’s standard conditions are. This is the minimum power level the player has during a determined segment of the game (be it a stage, a level or the whole game). This can vary often due to permanent power-ups.
* Find the base enemy (generally the weakest or most generic enemy) and set its threat level to 1, and adjust the threat level of all other enemies in accordance to its stats.
* Playtest. A lot. Have different players with different play styles move through the level so that you can get the average time (if doing time-based difficulty charts) or average distance (if the chart is distance-based) of each enemy encounter.
* Check which situations you find the enemies in, and assign values to those situations depending on how the mechanics and enemy behaviors allow you to fight them.
* Determine how the encounters work. Figure out how many waves there are in each encounter and what enemies they are composed of.
* Ʃn=0 = (Etn)(ESn) Multiply each enemy’s threat level by the situation multiplier and add them all up for each wave.
* Plot them in a graph according to the time when they appeared or the distance from the starting point where you meet them.
Just to show an example of how they look, I followed this method to plot three different 2D sidescrolling shooters using time-based difficulty graphs. The games chosen come from different consoles and different eras just to show that this method is universal (and because they’re the ones I had easy access to).
The example games are Metal Slug (published by SNK in 1996 for arcades), Shank (developed in 2010 by Klei Entertainment; this test is based on the PC version) and Hard Corps: Uprising (created by Arc System Works in 2011 for Xbox Live Arcade and PSN).
Now, they might seem quite similar on the surface, but they have several nuances that make them different. This is important to mention, because the difficulty graphs do not actually show which game is harder. Remember that the difficulty is measured based on the game itself; a 1 in Shank is not the same as a 1 in Metal Slug.
What the graphs do show us is how the difficulty changes throughout the game, and this in turn gives us clues on the pacing and tension building of the game. Lots of spikes and you can bet it’s a fast-paced, tense game; lots of plateaus and it’s likely it is calmer.
Note: A great method for directly measuring pacing is Ben Cousins’ method of counting player actions. He describes it in his article Elementary Game Design, which you can find at his personal website, http://www.bencousins.com.
These graphs show the first level of each game from start to right before the boss. I’m leaving out boss encounters because they generally change the rules, requiring specific mechanics for victory. Comparing them directly with the rest of the level can cause gargantuan spikes in the chart that are not really representative of how hard the game is overall.
First up, Metal Slug, the shortest of the bunch (clocking at around 1:20). We can see that it presents enemy encounters every two to three seconds. Besides your standard pistol, the game starts you with some grenades, which are a hard-hitting, though limited, weapon. Unlike the other two, it features one-hit-kills (another way to say all enemies do the same amount of damage) and hefty temporary power-ups, including the titular Metal Slug (a tank, basically). As an arcade game, death isn’t a big deal, as each continue will respawn you at the point of death. This is, of course, until you run out of quarters.
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We can see that the basic trend is quite close to the horizontal axis, with a smooth rise throughout the level. There are two large spikes which represent helicopters. Under standard conditions they are quite tough (taking around 40 shots from your basic pistol to take down). The camera freezes and stops your movement until you kill them, making sure you can’t just skip ahead, explaining the plateaus.
To help you out, the game provides you with power-ups (red vertical lines) right before facing them. As all power-ups in Metal Slug are temporary, the game makes sure you have at least one by dropping a bunch of them really close to one another.
There is another rather large spike near the end, once you start facing other tanks. Provided that you still have your Slug, they should be no problem; however, if you lost it to the helicopter, you could be in a tough spot. The game balances this by giving you health for your tank (the green vertical lines) right after the second chopper and just before the tank section, again trying to make sure you don’t miss out.
Next we have Shank, whose first level is around five and a half minutes long. Contrary to Metal Slug, you have a health bar in the game, so enemy attacks aren’t so devastating. Also the game starts you out with four weapons (pistols, knives, a chainsaw, and limited grenades) allowing you to take on several enemies at once. On the flipside, there are no power-ups except health and more grenades, so what you start with is what you get.
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At first glance, we can see that the game is a slower-paced than Metal Slug, due in large part to having clearly-defined encounters in which the player can’t move ahead. We can also see that in most encounters, enemies appear drip by drip, leading to the stair-like form of the curve. The obvious point of this is easing the player into combat, instead of presenting the challenge all at once.
Between large encounters (which can be distinguished by the high plateaus), we find that the game always presents a couple of enemies, so that the challenge never gets too low.
Just like in the previous example we have a spike near the end — however, this is an absolute spike, presenting the hardest part of the level. After this we see a steep decline until we get to zero, the complete absence of enemies and obstacles, in preparation for the boss battle.
Interestingly, we see that health packs are commonly found in the middle of the encounter (usually because they are enemy drops) and tend to be found more frequently at the later stages of the level. On the other hand, only once can we restock grenades; this is most likely due to the game trying to get the player to learn to use his three main weapons.
Lastly we have Hard Corps: Uprising. In this game, the player has a segmented health bar, with the base enemies taking a full segment with each hit. Though the player only starts with a weak machine gun, she is able to pick up several power-ups which are lost when hit. The first level (minus the boss) clocks in at around 6:20 and is easily the longest of the bunch.
Despite having an Arcade Mode (no character building), the game’s star attraction is the Rising Mode, which allows the player to gain experience and permanently upgrade her character even if she dies. In other words, it allows for grind.
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First off, you’ll notice the off-the-chart spike; I intentionally left it there. This is the miniboss (the typical Contra wall). Clearly its power is off the roof — it takes many hits to bring down and has powerful attacks. However, once you battle it, you’ll notice the terrain gives you a great advantage against it, so in the end it’s not really that tough. This is why it’s recommended to treat your boss fights as special cases. They work differently, often with different rules and game mechanics — hence, they don’t really relate with the whole level.
Putting the miniboss aside, we can see that the game has a very spiky difficulty curve, with short plateaus and lots of ups and downs. This is decidedly a fast-paced game. Despite its ups and downs, the mean does tend to go up throughout the level, with longer confrontations and more enemies being faced at a time.
While encounters near the beginning of the level are at around seven, near the end they reach 30. This is a massive slope in difficulty, perfect for a grind-friendly game. Near the end we once again find a major confrontation followed by a brief respite before fighting the boss. Notice that power-ups are evenly distributed throughout the level, as they form an integral part of the game mechanics. On the other hand, health is much rarer, though it is also found at equal intervals.
We can compare all games’ graphs by simply normalizing the time (dividing it by their total length) and plotting them together. Once more, this is not a measure of how difficult a game is, but how that difficulty changes. Here we can see that in all three games, the difficulty curve’s mean is below 10, which is quite usual for first levels. Hard Corps is the one with the highest change in difficulty, while Shank is a lot more constant. Metal Slug is also quite constant with few (though large) spikes.
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If we start thinking about the overall design of each game, we see that these differences make a lot of sense. The grind and permanent power-ups of Hard Corps allow it to have a steep difficulty curve throughout the level, and actually encourages the player to start over several times to pass it. Meanwhile, arcade Metal Slug, which is trying to suck you out of quarters, depends on minibosses to provide challenge, allowing you to beat them in multiple tries (as long as you pay). Shank, on the other hand, seeks accessibility, having a smooth curve, which allows new players to ease into the game.
Analysis by difficulty graphs tells us a lot about a game — not only about the way it’s structured, and the way it looks for engagement, but also about the design philosophy behind each game. It’s also useful while designing your own games as an analytical way to find spikes and valleys that shouldn’t be there.
Of course, this is not the only method of measuring difficulty; however, this has been very useful as it is independent of individual player skill. Once the results are in, everyone in a team can easily see where the trouble spots are, and it makes tackling them together a lot easier. I really recommend you give it a go. You’ll be surprised how much this makes difficulty easier.
篇目2，Difficulty: Challenge vs Frustration
04/10/2013 Despain Game Design 7 comments
Today’s topic is one that is important for all sorts of game design: difficulty. There’s lots of ways to make your game difficult, but unfortunately most of those ways are shortcuts that don’t lead to appealing gameplay.
Lots of game developers will feel the need to make their game more difficult, so they add all sorts of “features” that only end up making the game more frustrating. “But the player is dying more often,” they say, “it’s a challenge.” Well, kind sir—is it really a challenge? Or is your gameplay just hard for no real reason?
Today we’re going to look at the difference between challenge and frustration, and how to add to your game’s difficulty curve while avoiding making your players feel bad about it.
People overlook the importance of a difficulty curve. Sure, most people understand the basic idea: the game starts easy, and it gets harder as it goes. Unfortunately, there’s more to the idea than that. It’s not just about how hard the game gets, but in which ways it becomes more challenging to the player.
I could easily write an entire article about difficulty curves and training the player (and maybe I will!), but for now, I want to cover some important ideas about how to establish a difficulty curve that makes sense for your game, and won’t annoy your players.
I’ve seen a lot of games that start out smoothly and easily, but then you get past that “beginning”—and wham!, the game becomes incredibly difficult as soon as your turn that corner or enter a new area. What happened to the idea of curve? Keep it natural and gradual, and do so by putting the player in situations where his ability is tested.
That’s the most important thing to keep in mind when trying to create a difficulty curve for your game: a game’s challenge lies in the way it tests the player’s skill at that game. Simply making enemies have tremendous amounts of HP usually isn’t the best way to do that. The player should feel like he is overcoming obstacles, that he is getting better at the game the further into it he goes. A good difficulty balance is one that tests the player’s ability, not his patience.
As the game progresses, it’s easier to feel the need to artificially ramp up the difficulty, by doing things like giving enemies ridiculous amounts of HP, or giving them moves that kill player characters in a single hit. Sometimes these things make sense—but if you don’t have a reason for them other than to make things “hard”, then think about other ways to add to the challenge.
Build on the gameplay that has come before, and throw new situations at the player. Give him a reason to use the skills that he has developed in new ways.
There’s a reason that most players prefer RPGs that encourage strategy in battles over level grinding, and that reason is because they like a good challenge, not frustration.
So what exactly is frustration? What causes it? What makes a player want to turn off the game and never play it again?
Frustration occurs when the player feels as if his time has been wasted, and that the game is at fault.
There are two important parts to that statement, so let’s break it down. The first part has to do with the value of a player’s time, which is an important concept to understand in modern gaming.
Thirty years ago—or twenty—or hell, ten—players valued their time differently. Games back then were a lot harder (and a lot more frustrating) than they are today. This isn’t to say that players’ time was less valuable. Accessibility to videogames was different, and gamers didn’t have the luxury of thousands of games available to them at a moment’s notice. In today’s world, if someone doesn’t like your game—maybe because they feel that it’s not worth their time—they can just delete it and find another one within moments. Twenty years ago, if a game frustrated a player, they didn’t really have that option, so they kept pushing through until the game was beaten.
Gaming culture has changed, and game design changes to accommodate the lifestyles of games. You can’t get away with wasting your player’s time.
So what is a waste of the player’s time? Think about the times that you have gotten mad at a videogame. Maybe you died and were forced to replay a huge area—maybe you were forced to sit through that long cutscene again and again. Maybe you were just about to land the final blow on a boss that you’ve been fighting for an hour, and he hits you with a cheap shot, leaving you to do it all over again. Or maybe you find yourself in a random battle every other goddamn step you take.
ONE MORE STEP
No Zubat… no Zubat… please no Zubat…
The second part of my definition of frustration is key for a game designer to understand and constantly work into his gameplay. When something goes wrong, the player blames the game, not himself.
Obviously, the biggest example of this is a glitch. If the player’s going along, having a good time, and gets stuck in a wall, he isn’t very happy, and he did nothing wrong. Those aren’t intentional, though. What about aspects of gameplay that leave the player howling at their monitor?
Camera problems are a common cause of this in 3D games. It happens all the time—you miss a jump when the camera suddenly rotates, or a wall is blocking your view of your character, or enemies are attacking you and you don’t know where they are coming from. The player feels like he has no control, and the last thing you want your player to feel is that he isn’t in control.
In RPGs, these kinds of problems are harder to pinpoint, but no less frustrating. Here’s an example that seems to come up a lot. Picture the classic block pushing puzzle, and the player somehow gets a block stuck in a corner. Uh-oh. He has no choice but to leave the room, reset the puzzle, and start all over again. “B-b-but the player shouldn’t have done that”, you say. I counter with “he shouldn’t have been able to.” Design your maps in such a way where blocks can’t get stuck in corners, or (preferably) allow the player to pull them as well as push them. Avoid situations where your gameplay allows your player to get trapped.
Here’s another example, going back to the idea of random encounters. Say that your player has fought his way through a tough dungeon, and his party are all sitting at a dangerously low HP. The end is in sight, so he goes for it. But nope! The screen flashes, and he’s in a battle. He tries his luck, chooses to flee, and fails. The monsters kill the player. These kinds of things can be avoided with some simple gameplay tweaks. For one, maybe monsters don’t attack on the same turn when a player tries to flee. Sure, it makes the game easier, but it prevents situations that cause frustration. Or maybe you could just drop random encounters altogether.
Even without random encounters, your player can find himself blaming the game for out-of-nowhere deaths. When working with visible enemy encounters, think hard about where the enemies spawn and how they move. You want to allow the player to dodge them (most of the time), and you don’t want to clutter the screen to the point where he panics. Incorporate your encounters into your level design, rather than just plopping them here and there.
Scour your gameplay for areas where the player dies and it isn’t his fault. Push yourself to find ways to give the player control of his fate.
So we know what causes frustration. That makes for bad difficulty. What makes a game difficult in a good way? Challenge.
Challenge is a test of the player’s skill. Any failure feels like the player’s own fault.
I’ve talked about testing a player’s skill. That’s what a player wants as a game gets more difficult. They don’t want to grind their way through hours and hours of the same things. They want to be put into situations where they can use the skills that they have been developing, and often in new ways. Think about the mechanics of your RPG. RPGs are thinking games, for the most part.
Encourage your player to think, to use strategy. To make the most out of the mechanics in front of him. Don’t throw everything that you have at the player from the beginning. As the game goes on, present the player with a new type of problem that can be solved with the same tools that he’s been using. In a battle, in a map puzzle, the idea is the same. And as the game continues to go on, mix the problems together, and introduce more. Sure, make the enemies harder, make the puzzles more complicated, but remember to challenge the player to think.
An RPG doesn’t get more difficult when the enemies have higher HP. It might be harder, but the difficulty dwindles. If all the player has to do is grind and then he can just bash his way through the battles, then he’ll get bored quickly. Challenge the player’s mind.
The second part of my definition is, again, about blame. When the player messes up, in a good challenge, he has nobody to blame but himself.
The final level in Super Mario Galaxy 2 was hard, but rewarding—every time you died, you felt that you made a mistake and you learned something for your next try.
Now, I’m not saying that the player should be getting mad at himself—that’s easily frustrating. But instead, every death should be a learning experience for the player. He should be able to pinpoint the mistakes he made so he can improve on the next time. If a player dies, it should give him the chance to change his approach to the challenge. Maybe he’s tackling a boss from the wrong angle, and his death teaches him to try another strategy. Deaths should lead to learning.
That’s the important point: a good challenge can be overcome by the player’s ability to adapt to the situation. A good challenge encourages the player to do his best. A good challenge makes the player want to keep playing the game.
And frustration just makes him want to give up.
by Corey Moore
Of the games I’ve played over the years, I’ve noticed something. Very rarely did I end up beating my older games, yet with more modern games I either beat them or lose interest. Of course, I’ve had many years to improve my technique and some games where I was too scared to progress don’t scare me as much today. However, I’ve gone back and played some old games and they ended up killing me. Games today are a lot more forgiving than they were back when DOS and the NES reigned supreme. Maybe it’s just me, but have you ever noticed how many people today say they’ve finished a game rather than they say they’ve beat a game?
“That’s the way it was, and we LIKED IT!”
I’ve heard a lot of descriptions of games today compared to games of back when. “Dumbed down”, “Made for ****ing casuals”, “Mainstream” and “Simplified” all come to mind. An easy game isn’t necessarily a bad game, but many gamers demand a challenge. Games quickly become boring if the player isn’t sufficiently challenged, and eventually, the player may elect for a self-imposed challenge just to spice things up.
There are several kinds of challenges that gamers like to perform, depending upon the game’s genre. Some of them include only using the default gear, getting the lowest completion percentage possible, or go through the game without taking any damage at all. Many games throughout the ages recognize players who complete the game 100% or complete the hardest difficulty, but only few recognize those challenges that fans come up with. One notable example is Shadow Complex, which has an achievement for getting the lowest percentage possible and still beating the game.
While creating a sufficiently difficult game is vital to creating a good challenge, the difficulty should still be fair. Difficulty must never come from bad game design. Sure, a game where the vital plot coupons are in obscure locations that require a series of illogical triggers to even make visible and several more to collect may definitely make a difficult game, but a good challenge it does not. All it does is force the player to wander around aimlessly, fidgeting every button at everything hoping for a reaction of some sort. Imagine if Myst didn’t provide any ingame clues as to where you are supposed to go and what you are supposed to do. Instead of being remembered as a classic, it would be remembered as an incoherent mess of a game.
In a Gamespot review of Metroid Prime 3, one of the things the reviewed marked the game down for was that the controls were too good, as if the Retro should have purposefully made the controls worse to up the challenge. There is no such thing as controls that are too good. It’s one of the prime factors that separate a good game from a bad one, and purposefully making bad game design choices is a lazy way of creating difficulty. In fact, I could easily make any game harder by smacking the player in the face every 3 seconds while yelling, “boogity-boogity-boo.” It wouldn’t be fun at all, but still challenging.
Another thing that should be avoided especially is trial-and-error game play. In a good game, the payer should be able to collect all of the knowledge needed and beat the game in one clean run. Forcing the player to play through multiple times just to find the correct path is not only an example of bad game design, but also an example of difficulty that disappears over time. Although it’s hard the first time, it becomes an absolute joke the next time. Note that this is different than simply needing practice to get through hard sections of the game. It does seem like trial and, though the end result is much more reward and even after you complete it, it still isn’t easy the next time. Some unexpectedness can keep a game interesting, but if every task is overcome by playing through over and over, there is a problem.
Dirk the Daring: Patron saint of trial-and-error gameplay and using quicktime events before it was popular.
However, for all the complaints about games becoming easier these days, there are still some modern examples of extremely hard games. One of the more famous ones is I Wanna Be the Guy. The game controls well and provides a nice throwback to the days of 8 and 16 bits, but it is also extremely difficult. On almost every screen, there is something hidden that can kill you in one hit, and it often comes from where you least expect it. Even if you know where the traps are and how the bosses move, you will still need all of your platforming, shooting and dodging skills to make it through the game. True, it relies a lot on trial and error, but it still remains hard even with prior knowledge. Another good example is Halo 3. In additional to the brutal Legendary mode, there are also hidden skulls which add even more challenges, such as having no checkpoints, no radar and enemies being able to dodge your shots.
Should all games strive for I Wanna Be the Guy-level difficulty? Certainly not, simply because that is not what every gamer wants. Some people would rather enjoy the story and others don’t want the game to be absolutely merciless. This is all perfectly fine, despite several people who would proclaim that you are playing it wrong. The main point is not to forget about the gamers who’ve already beaten your game and want a bigger challenge, but have to create their own. By providing these challenges, not only does it show a connection to the gamers who have invented them but will also add longetivity to the game.
Although we frequently have discussions about difficulty in games – is it too hard? which parts did you have trouble with? was it too easy and therefore boring? – we rarely direct our attention to the different fundamental types of difficulty which make up our experiences and colour our perceptions of the challenge a game provides. In this article, I’d like to go over a few of those most basic types of difficulty as well as the problems associated with implementing them, as well as bring out that it’s often not just the sheer challenge of a game that matters, but the nature of those challenges that matter.
Trial and Error
The first, and most obviously identifiable type of difficulty that we find in games, and by far the most common, is trial and error. Put simply, trial and error revolves around getting the player to perform a task, either through experimentation (i.e. “I don’t have anywhere to go, maybe I’ll try this”) or outward suggestion (i.e. “these are your orders, soldier, now move out!”). At least theoretically, the main difficulty this presents to the player is that the degree of challenge (types and numbers of enemies, for instance) will always be slightly higher than what the player is comfortable with, meaning that he or she will have to rise to the occasion in order to come out on top, either by trying out new tactics, by taking greater risks, or through sheer force of will and/or dumb luck.
As many of us can attest, trial and error difficulty treads a very fine line. Typically, too many failures, and players will become frustrated, while too many successes and players will feel as if the game isn’t going hard enough on them. The main issue with this, aside from basic balancing, is that different players have different thresholds for difficulty. Whereas a more casual player who’s just enjoying a game for its story will find that more than the occasional death is a turn-off, the hardcore player who plays on the “insane” setting will want to be challenged at every turn and made to work for every single victory. Ultimately a developer might run into a situation where they’re balancing not just one, but three or four versions of the same game, due to the different needs of different players.
Of course, pacing is also a chief concern by and large governed by the ebb and flow of difficulty, usually of the trial and error nature. The player needs to have portions of the game which fly by quickly and without too much issue, breaks in combat to absorb the world and feel unchallenged, and nail-biting experiences that are tense and have a feeling of urgency to these. Building these into a game when taking different gameplay preferences into consideration is a difficult process; after all, while it can be easy to balance a single encounter out to give the player the desired experience, doing so within the context of a full game is another thing entirely.
Adaptive difficulty settings are one way to get around this problem. On the most basic level, this will typically change the amount of resources (health, ammo, etc.) provided to the player, as well as the proportion of powerful versus weak items based on the player’s performance (i.e. more “full heal” pickups if the player is struggling). This feature is actually extremely common in games, either because developers want to avoid providing separate difficulty levels (a poor decision in my mind), or because players have a curious habit of selecting difficulty levels that aren’t appropriate for them (everyone has a different understanding of what “normal” should be).
Adaptive difficulty can be both explicit and hidden from plain sight. Prey, for example, has adaptive difficulty as a toggle option in the game’s options screen, and so it can be disabled based on the player’s preferences. Half-Life 2, on the other hand, while providing three difficulty settings (easy, normal and hard) also has a layer of code dedicated to analyzing the player’s progress in the game, level of resources, the ease at which certain encounters are completed, and so on; the game will then adjust the items enemies drop, the amount of resources available in breakable crates, and so on in order to make sure the player is always kept on edge by having “just enough” health and ammo to get through an encounter, but never quite enough to feel completely safe or fully-loaded. Other games will implement it in still subtler ways, like allowing the player to finish off a tough boss monster just a little bit more quickly than normal if the player’s death is imminent, creating a dynamic feeling of getting through by the skin of his or her teeth.
The biggest issue for me with adaptive difficulty is that, when left as a built-in feature that can’t be disabled, it removes control from the player’s hands.
Although I’ll usually take an entertaining and engaging experience over one that’s simply difficult for the sake of difficult, I also fully understand that some players don’t want hand-holding provided that they explicitly ask for it. Furthermore, adaptive difficulty can also lead to a feeling of predictability and sterility, without a hand-made feel to encounters (which was a major source of criticism for The Elder Scrolls IV: Oblivion). To this end, I feel that adaptive difficulty is best left as it is in Prey – a toggle switch in the options menu – or specific to a difficulty level, with the hardest mode taking off all assists, which mitigates the problem of too much challenge by allowing the player to rationalize it as his or her own choice (i.e. “well, I picked hardest, I should have known it would be too much for me”).
Endurance & Attrition
Another way to test the player focuses on the long term rather than the short term. All forms of endurance, at their most base level, revolve around resource management, with the player given a limited quantity of a valuable or vital item, its distribution carefully controlled. Resources are controlled in three main ways in just about every game:
1) “Random” drops. It’s quite common for enemies to part with valuables when defeated, or for the player to uncover supplies in crates, chests and so on. By tinkering with the tables that control those supplies, based on difficulty, the player’s progress, the amount of resources the player already has, and the player’s level of ability, character level, number of party members/companions, and so on, difficulty can be precisely controlled and monitored in order to provide a degree of challenge.
2) Attrition rate. Depending on the game, the rate at which a player burns through supplies can be highly variable. For instance, in a shooter, going up against a tough boss monster might not consume too much ammunition, but may consume a huge amount of health. Conversely, going up against many smaller hordes of enemies will end up with a player ill-equipped to proceed, but chances are, a healthy one. Learning to anticipate what the player needs in order to continue in the game is important. If a game uses an adaptive difficulty system, this might already be handled, but even so, careful consideration of how quickly the player goes through certain resources will lead to better encounter design and a game that feels more alive and responsive to the player’s needs. Strategically denying certain resources can be just as important as strategically providing them, too, in building tension and pacing the player’s progress.
3) Player ingenuity. Most common to role-playing games, smart players will often stock up on useful items like potions and ammunition before heading out into a difficult encounter; the duration the player can stay out in the wild before returning to stock up on supplies again is by and large controlled by the player’s prior action, as well as whatever the player might uncover during his or her outing. This is one thing that is hard to control in a game, and frankly, shouldn’t be. Keeping aware of what players can and can’t do, and building challenges around that is a good thing, as are systems, such as encumbrance and fatigue, which can provide a soft limit on how much the player can carry. However, imposing unreasonable hard limits (i.e. “you can only hold three health potions at once”) rarely feels like a fair way of managing this.
Long-term attrition may not be suitable for many games, but looking at attrition in different ways can actually reveal interesting opportunities for mechanics that may go unnoticed with a casual glance. For example, a puzzle game like Tetris has a strong element of attrition in the sense that the available space on the game board is continually shrinking based on the player’s performance, the difficulty level, and which puzzle pieces the player is provided with. On top of that, game speed is another gradually-depleting resource the player must carefully manage as things move quicker and quicker over the course of the game. There is a veritable economy of space and time in Tetris, even though there is no health bar, ammunition counter, etc. to speak of. Recognizing that attrition and endurance can exist as more than just basic physical resources will help flesh out and provide depth to existing mechanics.
A subset of trial and error difficulty, what I’ll term “fake difficulty” here is something which is actually quite common in the games industry, but depends a good deal on the genre in question. Fake difficulty is a fairly broad spectrum of difficulty, but in common with all of the various permutations is the fact that they typically revolve around tricking the player or bending the rules of the game in order to provide their challenge – often causing significant frustration and annoyance for players, whether they’re keen to those tricks or not.
One of the most common forms of fake difficulty actually fits within the category of adaptive difficulty – namely, it revolves around manipulating the rules of a situation in order to provide the player with increased challenge, usually referred to as “rubber-banding”. The key difference is that while adaptive difficulty works in favour of the player (for example, you’ll find 50% more health kits if you’re low on health), fake difficulty tends to work in favour of the enemies or opponents.
However, since enemies rarely compete on fair terms with the player, and in fact tend to use an entirely different set of rules, this usually means that the bonuses given to the player’s opposition fall into the realm of super-human – increased speed beyond normal limits, temporary damage boosts, the ability to negate the player’s own abilities when normally they can’t, and so on.
A great (and persistent) example of this type of difficulty can be found in Mario Kart – in fact, the series is somewhat infamous for it. While the goal of the game’s rubber-banding is to provide a tense and exciting experience for the player, making sure that each race is as close a finish as possible, and that enemies are able to always keep players on their toes, in the long run, or for more experienced players, this form of difficulty tends to only breed contempt. While the illusion created is often enough to fool players who are of a lower skill level, as the effects are much more subtle and can often work in the player’s favour, when that same system is put up against players who are able to make a mockery of even the high difficulty levels, the computer is forced to go to incredible levels to try and keep up with the player, to the point of blatant cheating, gaining items and abilities far in excess of the player, and even defying the laws of physics (or whatever analogue exists in the Mushroom Kingdom).
Another form of fake difficulty that rears its head is that of the false challenge. In the false challenge, the player is typically asked to perform a standard feat – defeat some enemies, race to the finish in the allotted time, etc. However, what starts out as a relatively routine task quickly turns out to be an extreme test of reflexes and ability, as the player is beset with all manner of unpredictable obstacles, traps and powerful enemies. The key thing is that in all of these situations, the player is caught off guard, and unable to sufficiently prepare. Usually, this results in a quick and frustrating death, as the player likely felt he or she was successful up until that point. Worst, usually, the only way to surmount this type of challenge is to try it again, often from the very beginning of the sequence, armed with the foreknowledge of the hidden challenge ahead. When these are compounded one after the other, it can lead to rage-inducing moments for the player.
One game series which is notorious for this is Grand Theft Auto. While the game’s mission-based structure suggests that the challenges faced are relatively self-contained and straightforward, it’s very common for the games to prey on the player’s expectations in the worst way possible. One example from Grand Theft Auto: Vice City I frequently cite is a race sequence where the player has to reach a number of checkpoints in a set time. No big deal, right? That would be the case, if it wasn’t for the fact that other cars, trucks etc. are scripted to pull out around difficult corners and immediately as the player passes by at full speed – the player is almost guaranteed to hit these cars and ruin his or her attempt outright, unless he or she is able to slow down and let them pass instead. This just doesn’t happen once, but close to five or six times throughout the race, meaning that even if the player does everything right, there’s still a huge statistical probability that he or she will fail anyway, solely due to the designers pulling a fast one. A similar occurrence can be found in Max Payne, where enemies are scripted to throw grenades at the player at certain triggers, and these are literally impossible to avoid without prior knowledge.
Suffice is to say, fake difficulty, no matter the variety, isn’t fun for players, even if it’s built into the game with the best of intentions. Although often the goal is to provide an unpredictable or challenging experience regardless of the player’s skill level, more often than not it just comes across as mean-spirited, and at worst, can completely turn a player away from the game by rendering attempts at competition null and void. Unlike most forms of difficulty, this type is actually best avoided altogether, unless your goal is to make players hate your guts.
Random Number Gods
Although this is typically a type of difficulty reserved for strategy and role-playing games, random mechanics do exist in a wide variety of genres, whether they manifest in terms of how enemies behave in combat, the spread and accuracy of weapons, or whether or not the player is able to sneak by a foe successfully.
I’ve occasionally seen mechanics based on random elements derided by people, claiming that it takes away from the skill of the player to hinge success upon unpredictable odds. The key thing to understand about building difficulty out of a random number generator is that challenge is not substituted for “luck”, as some might claim. Rather, difficulty arises as the player is forced to respond intelligently to new developments that aren’t entirely predictable – it is the culmination of actions over a period of time that are important, not the individual actions themselves. Unlike trial and error, which typically tests reflexes and coordination, systems built on random elements test the player’s ability to respond to change and to cope with new situations.
As mentioned above, it’s also important to mention that random elements are often a staple in all types of games, regardless of whether or not difficulty is provided by trial and error, by manipulation of odds, or, ahem, fake difficulty. Driving a car in a racing simulation, for instance, there’s bound to be some random effect in the vehicle’s handling, or on varying types of terrain, even if it’s only a small piece of the overall picture. There is absolutely nothing wrong with this, because usually player skill is able to account for random elements anyway. More to the point, random doesn’t necessarily mean unpredictable – it just means that there can be a certain degree of noise or interference in playing the game, to prevent things from playing out exactly the same way every single time. Otherwise, when playing Tetris, we’d see the same blocks always become available in the same order, and that wouldn’t be nearly as fun to play, as the game itself is based wholly around bringing a degree of order to that randomness.
Unfortunately, building systems out of random number generators, particularly in role-playing games and strategy games, it’s easy to fall prey to a problem – not in the mechanics themselves, mind, but in the player’s perceptions and understandings of them. This usually manifests as what’s commonly called the gambler’s fallacy.
The simplest example is a coin flip. Even though a coin only ever has a 50/50 chance of landing heads or tails (assuming it’s a fair toss), we tend to assume that the 50/50 probability applies to all instances of the event in sequence, rather than the isolated event. In other words, we form a narrative as we flip that coin over and over again, perceiving each coin toss not as a single incident, but part of a larger whole – and as such, we also tend to assume that prior events have an influence on future events, or, put simply, that the more the coin lands heads, the greater the chances we think it has of landing tails.
In gaming terms, this can be described in the context of a turn-based role-playing game. A skill might have a 70% chance of success when used, yet we become frustrated when, turn after turn, the skill misses and we end up wasting both our time and resources trying to rectify the problem. What just happened? Surely, the game is fudging the numbers! Well, no, not really. We assume that, because the skill has a 70% chance of working, it should (or will) succeed seven out of ten times, like clockwork. This is, of course, not at all the case, as each individual attempt has the same odds as the last, and therefore, it’s possible to chalk up a huge string of losses despite what should be good odds.
There’s no easy solution for this problem, because you aren’t battling the numbers, you’re battling player expectations. Many developers actually get around this problem by instituting measures to make sure that random odds are, in fact, more predictable. For instance, if I have that 70% chance of success, I might program a clause into the game where it’s impossible to miss more than one time in a row – even if ultimately the math is completely off. That’s right, often, the random odds most players feel they rely on aren’t actually random at all, but instead manipulated to fulfill the expectations players have. The irony of all this is that usually the player only ever notices that there’s a “problem” if the math is correct in the first place. Obviously this is a controversial decision, and not everyone will agree with it one way or the other, but in the end it’s probably better to fulfill player expectations than it is for those same players to wind up frustrated over what they feel are unfair and incorrect odds.
Presentation is Everything
The header here might draw some ire, but I think that this is a lesson that is very much unsaid when designing games, and yet at the same time one of the most important to learn. Difficulty, as I’ve outlined, comes in many flavours and is highly subjective – however, it is also important to recognize that the way difficulty is presented to the player is also just as, if not more important. Similar to the gambler’s fallacy, sometimes it’s not a particular mechanic that’s the problem, it’s the way that players perceive it that’s at fault.
Let’s take a recent example in Dead Money, the Fallout: New Vegas DLC add-on. The game came under attack from both players and press alike for what they perceived as a steep difficulty curve. In Dead Money, the normal endless freedom of Fallout gives way to slavery, as the player is thrust into a very specific and mostly linear path through the game by way of a bomb collar, which will instantly kill the player if he or she strays too far for the beaten path. Many of the challenges in the game rely on destroying the radio transmitters that broadcast the detonation frequency, which are often hidden underneath tables, inside closets, or are otherwise difficult to reach. The goal in this situation is to create tension for the player as he or she desperately rushes to find the radio transmitter before his or her head is explosively removed.
It’s pretty clear, from an outsider’s perspective, to see why this mechanic would be frustrating to players. The bomb collar produces a high-pitched, persistent beeping when under threat of detonation, which players quickly learn to avoid like the plague, for one. There’s also something particularly demeaning about being enslaved in such a way by the antagonist. Other games that do this typically do so in such a way as so that the player regains his or her freedom quickly – while it’s a good way to breed contempt for the villain, draw it out too long and that contempt falls onto the game developer instead. Last, this kind of enforced limitation goes against what most players take the newer Fallout games for, namely, open-ended role-playing games with a variety of solutions for every situation; in Dead Money, frequently there is only one solution, and it’s often the one players aren’t happy with.
However, the problem with Dead Money isn’t the mechanic itself. Analyzed at a basic level, all it is a simple race against time to remove an environmental threat – turn off the switch before you die. The bomb collar mechanic, while effective in terms of the storyline, could have been replaced with any number of similar mechanics and still would have been just as effective. More importantly, it wouldn’t have been nearly as frustrating to players. For example, radiation and toxic hazards are extremely common in the Fallout world – why, then, didn’t Obsidian choose to instead implement the same threat in the form of radiation and, say, vents to clear it up? Interestingly, this variation actually exists in Dead Money, but is used to a much lesser degree. Had the bomb collar been replaced with a game mechanic which was functionally identical, but less at odds with Fallout’s design tenets, I think there would have been far fewer complaints about the game’s difficulty, because in that case, the challenge would have been perceived by players as fitting far better into Fallout’s world, and less limiting overall – after all, if it’s just radiation or acid blocking your way, that’s a much more incidental threat than the villain’s scheming, which if anything comes across as deliberate griefing.
Looking around, I think you’ll find more and more examples of perception of difficulty being a bigger problem than the difficulty itself. I can already think of a few off the top of my head – the jarring and repetitive taunts made by the bosses in Deus Ex: Human Revolution, for instance, are extremely grating on the nerves even if the boss fights themselves aren’t overly challenging with a little preparation. Usually, in fact, associating a character with a given type of difficulty (say, Boswer and his castles in Super Mario Bros.) can quickly cause players to become frustrated and annoyed in situations when that character is either already rather annoying, or when the game mechanics themselves aren’t enjoyable – it gives people a face to yell at.
This analysis, while far from complete, should have given a pretty good overview not only of a few different types of difficulty, but it should also have made understanding why people get upset at different types of games, different scenarios, and different sorts of difficulty a bit clearer. Creating and fine-tuning difficulty is always an ongoing process, and it’s extremely difficult to get it right for all players. Even so, hopefully this piece has shed some light on exactly why that is, and what steps can be taken at a more fundamental design level, in order to ensure that your game is fun to play, and challenging, without being frustrating as well.