作者：Daniel Achterman

这篇文章主要关注的是RPG游戏中的PvE战斗模式，但也可以运用于PvP战斗或其他类型的游戏中。

角色扮演游戏中有着大量的内容，每项内容都有着多个决定它们在战斗中所发挥作用的参数，比如剑的伤害、使用技能造成的额外伤害和23级强盗的总生命值等。

当你观测某个游戏区域或固定角色等级时，调整内容并不会太困难。你可以测试该区域并修改数值，直到游戏状态感觉良好为止。但是，假如大型游戏世界中有上百个关卡内容和多个职业，那么调整这种游戏的数值就要复杂得多。

如何在不进行游戏测试以及调整每个关卡中每种角色的前提下设置RPG内容数值呢？

有种计算方法可以帮助你迅速生成如此多内容的首批恰当数值。这种方法计算的是每项内容对角色战斗效能的影响，以通用单位来呈现影响力。

这使你能够以相同的标准来比较各种不同类型的内容，让你实现下述目标：

1、比较不同职业，并做出相应调整。

2、识别可能导致不平衡的道具或能力。

3、确定哪种类型的敌人将成为玩家角色的挑战。

4、得出技能或道具的参数值，让它体现出应有的强大之处。

最后一点特别重要，不是猜测，而是计算得出（游戏邦注：随后进行应有的修改）。

（在暴雪作品《暗黑破坏神》之类的游戏中，随着角色的升级，有许多因素会导致角色能力的提升。）

这不是个严谨的过程，需要进行大量的近似估算，而且对某些类型的内容并不适用。但是，对于其能够发挥作用的方面，你可以用它迅速生成参数值，而且准确率接近80%。

方法

步骤如下：

1、执行核心游戏玩法。如果游戏与你的愿景不符，那么也就没必要制作其他内容，因为修改核心游戏玩法会导致内容返工。要先制作出核心玩法符合愿景的游戏。

2、设计确定X等级角色的“基础能力”属性。“基础能力”由随角色升级而稳步提升的属性来决定，不受任何玩家选择的影响，包括生命值、基础攻击力、预期护甲或THAC0（零级命中值）。

3、识别其他随角色升级而加强其战斗效能的游戏内容。这样的系统有道具修改器、技能、《魔兽世界》的技能雕文和《英雄联盟》的符文。这些东西结合起来，形成了角色的“总能力”。

4、对于每项内容，以角色基础能力百分比来表达其数值。比如，2%的攻击加成就使角色的能力增加2%。“基础能力加成百分比”便是你将用来比较不同种类内容的通用单位。

5、要确定自己所期望的每种内容随角色升级对角色总能力产生的影响或效果。比如，每个技能点使角色的基础能力提升5%，那么在花费20个技能点后角色的能力就将是原来的两倍。

6、以每项内容的预期效能为基础，计算其参数。如果你知道某项内容对基础能力的加成，而且知道如何通过参数来计算其能力，那么你也可以反向计算出其参数。

基础能力

确定基础能力是件难事，因为每款游戏情况各不相同。我所见过的最好的确定方法是，随着角色等级的提升，所有角色属性自动增加，无需玩家做出选择。

《龙与地下城》中的角色生命值和THAC0便属此例。《魔兽世界》中的角色在升级时获得的属性提升是固定的，技能效能同样稳步提升。

预期秒伤和护甲也属于基础能力。虽然这些不会自动增加（游戏邦注：玩家必须找到新装备才能使其增加），但在设计游戏内容时，需要考虑到玩家装备的更新。

《魔兽世界》等游戏在设计内容时假设玩家正在使用的是适合该等级且带有基础属性的道具，因而无法更改的道具属性也成为基础能力的一部分。

能力加成器

能力加成器是能够更改角色战斗中基础能力的内容。随着角色等级的提升，它们对角色整体能力的重要性逐渐增加。以下这些均属能力加成器：

1、技能点或天赋点。每点使角色能力增加1%。

2、诸多RPG中的道具加成器。等级越高，它们的数量和重要性提升。

3、《最终幻想7》中的Materia。随着玩家在游戏中的进展，玩家会获得更多强大的Materia，一次性能够使用的数量更多。

（随着玩家获得更多slots和Materia，Materia对《最终幻想7》中角色能力的影响逐渐增加。）

通常情况下，玩家会选择他们想要用来定制角色的能力加成器，而且不同职业使用的能力加成器也有所不同。做好职业间平衡的关键就在于，确保他们可用的能力加成器拥有平等的效能。

将能力加成器数值表示为基础能力的百分比

将能力加成器的数值以角色基础能力百分比的形式来表示。“基础能力加成百分比”是用来比较不同类型加成的通用单位。

因为所有的能力加成器都以基础能力为基准，所以我将各等级的基础能力设为1，也就是100%。未经加成的等级1角色的基础能力为1.0，等级54的角色的基础能力也是如此。如果某个能力加成器使角色的效能提升5%，那么其值就为0.05。

要将加成转化为效能，就要计算此加成器对角色在战斗死亡前所提升的伤害。假如某个加成器让角色的持续战斗时间延长1倍，那么也就相当于角色的效能变为原来的两倍，那么加成值就为1.0（游戏邦注：加成比例为100%）。

各能力加成器往往在特定的等级才可用，而且会设计为适合该等级角色使用。比如，在《暗黑破坏神2》的道具设计中，以角色当前等级的基础属性为参照来决定道具加成的百分比值。举几个例子：

百分比伤害加成

假设某个技能能够使角色的群伤提升1%。这个技能是针对群伤角色而设计的，假设他们总是能够从这项技能中获益，那么其值就为0.01。

条件伤害加成

一把剑有5%的机率使攻击伤害提升30点。那么，平均每次攻击伤害提升为1.5。如果每次攻击的基础伤害为100，那么其值就为0.015。

百分比生命加成

10%的生命值加成会使角色的存活时间提升10%，从而时他在战斗中造成的伤害总量增加10%，所以其值为0.1。

护甲加成

假设某护甲加成能够使角色的抵抗性从承受75%的攻击伤害提升到仅需承受72%的攻击伤害。也就是说，他承受的攻击伤害是之前的96%，存活时间是原本的1.04倍。因而，加成值为0.04。

总能力

角色获得的每项能力加成器都会提升其在战斗中的效能。他的总能力等于基础能力和所有加成器的总和：

总能力=基础能力+所有能力加成器

能力与角色等级存在一定联系，所以更精确的公式应当是：

等级X的总能力=等级X的基础能力+等级X的所有能力加成器

记住，所有等级的基础能力都被定为1.0。因而，所计算出的角色在等级X时的总能力的数值是与未加成前基础能力的比值。

总能力的进展

在调整怪物等玩家敌对势力的内容属性时，设计师需要关注的是总能力。作为设计师，需要对游戏过程中各种能力加成器对角色效能的提升数值做出决定。

各系统对能力的加成率有所不同。技能系统可能在每个等级中对总能力的加成是1%。解锁新能力或许会让总能力获得质的飞跃。玩家会将大部分注意力放在能够对其能力产生最大化影响的内容上，所以系统数值的分配就以该系统对游戏设计的重要性为基础。

以下是一个总能力进展的实例。在等级1时，没有能够发挥作用的能力加成器，所以总能力等于基础能力：

等级1总能力=1.0

在等级10时，玩家有9个技能点数，每个的价值为0.01。他还获得了来自道具加成器的加成，能力提升5%。

等级10总能力=1.0+0.09+0.05=1.14

在等级25时，玩家有24个技能点数，其道具加成器的值约为27%，而且他解锁了超级能力，使能力又提升了20%：

等级25总能力=1.0+0.24+0.27+0.2=1.71

换句话说， 普通等级25的角色的能力是无加成装备、不使用技能点数和不使用超级能力的25级角色的1.71倍。角色的总能力随时间提升的情况如下图所示：

在这个图形中，技能提供的是线性能力加成，道具加成器提供的是二次方程式加成，能力解锁提供的是每数个关卡的能力大幅提升。紫线显示角色在每个等级时的总能力，设计师需要根据此曲线来设计怪物。

计算能力加成器的值

现在，你已经确定了角色在游戏中的预期能力进展，你可以由此来计算各内容的能力加成值。比如，如果等级X角色应当从道具加成器处获得0.05的加成，而且在该等级下角色可能获得10个加成器，那么该等级下加成器对能力的提升应当是0.005。

计算出特定内容的能力加成值后，就可以得出能够赋予该内容特定能力的参数值。以下是两个实例：

1、条件伤害加成

10级剑有5%的几率使角色的攻击伤害提升X点。假设10级修改器的能力提升为0.06，每次攻击的基础伤害为100。这样，平均每次攻击伤害加成为0.06X100=6。用伤害加成除以概率就可以得出X。X=6/0.05=120点伤害。

2、护甲加成

10级头盔拥有能够提升护甲的加成器。10级加成器的预设能力加成为0.06。从护甲加成的角度来看，这意味着角色的存活时间应当是原本的1.06倍。因而，他承受的伤害应当是原来的1/1.06=0.94倍。假设在基础条件下，角色需要承受的75%的攻击伤害，那么在修改器条件下角色所承受的伤害应当是0.94X75=70.5%。

不适用该方法的情况

这种方法最适合用于RPG游戏中的PVE战斗。尽管它也能够被运用到其他类型的游戏中，但它与某些游戏设计无法兼容。

比如，在动作游戏中运用这种方法就显得较为困难，因为这种游戏中，根据玩家所使用技能的不同，伤害也会发生很大的变化。如果在某款RPG游戏中，战斗中会频繁出现将敌人撞飞的情况，那么可能也同样无法精确地估算加成值。

对于那些无法简单计算数值的游戏内容，使用这种方法同样很困难，比如对武器射程或咒语范围、移动速度、治疗能力和总魔法值的加成。

在设计上述加成元素时，要么通过复杂的数学模型来估算出数值，要么通过猜测和测试来找到恰当的数值。这两种方法都能够很好地发挥作用。（本文为游戏邦/gamerboom.com编译，拒绝任何不保留版权的转载，如需转载请联系：游戏邦）

The craft of game systems: Tuning RPG content

Daniel Achterman

This article primarily focuses on Player versus Environment combat in RPGs, though its methods can be applied to Player versus Player or other types of games.

Role-playing games have a tremendous amount of content, each piece with multiple parameters that define what they do in combat. Damage dealt by a sword, bonus granted by a skill, total health of a level 23 bandit, etc.

It’s not too hard to tune content when you look at a single game zone or a fixed character level – you can playtest that area and tweak values until the game feels right. However, trying to tune values for a giant world with 100 levels of content and multiple classes is much more complicated.

How do you choose values for RPG content without playtesting and brute force tuning every type of character at every level?

A computational approach can help you quickly generate first pass values for these massive amounts of content. The method is to calculate how each piece of content affects a character’s effectiveness in combat and express that “power” in terms of a universal unit.

That allows you to compare very different types of content in a mostly apples-to-apples way, enabling you to do a variety of powerful things:

Compare different classes and tune them relative to each other.

Identify items or abilities that are likely to be unbalanced.

Determine what stats enemies need to be a good challenges for characters.

Solve for the parameter values of a skill or item to make it as powerful as it should be.

That last one is especially important. Not guessing. Solving (then tweaking).

(Many factors increase character power as they level up in games like Blizzard’s Diablo III.)

It’s not an exact process. It requires a lot of estimating and approximating, and it can’t be done for certain types of content. However, where it does work, you can use it to rapidly generate parameter values that will be about 80 percent. right.

The Method

Here are the steps:

Implement your core minute-to-minute gameplay. Creating a progression of content won’t help if the game doesn’t play the way you want it to, and you’ll have to redo the work after you fix your core gameplay. Create a vertical slice of your game that plays the way you want.

Design the stats that define the “base power” of a character of level X. “Base power” is defined by the stats that improve steadily as a character levels up and which are not influenced by player choice, such as health, base damage, expected armor, or THAC0.

Identify other game content that magnifies a character’s combat effectiveness as he levels up. This can include systems like item modifiers, skills, World of Warcraft’s ability glyphs, or League of Legends’ runes. These combine to give the character’s “total power.”

For each piece of content, determine how to express its value as a percentage modifier to a character’s base power. For instance, a 2 percent damage bonus increases a character’s power by 2 percent. “Percentage bonus to base power” is the universal unit you’ll use to compare different types of content.

Choose what impact you would like each type of content to have on total character power as the character levels up. Should each skill point increase a character’s base power by 5 percent., so they’re twice as powerful after spending 20 points?

Given each piece of content’s intended effectiveness, solve for its parameters. If you know the intended bonus to base power you want a piece of content to grant, and you know how to calculate its power from its parameters, you can work backward to solve for its parameters.

Base Power

Defining base power is something I struggle with because it’s so specific to each game. The best definition I’ve found is that it’s the combination of all character stats that increase automatically as a character levels up, without involving any choice by a player.

Examples include things like character health or THAC0 in D&D. WoW characters get a fixed set of stat points when they level up, and skills increase steadily in effectiveness.

Expected damage per second and armor are also part of base power. Though these don’t increase automatically (the player has to find new gear), game content tends to be designed with the expectation that players are maintaining up-to-date gear.

Games like WoW assume that players are using items with base stats that are appropriate for their level, so unmodified item stats are part of base power.

Power Magnifiers

Power magnifiers are pieces of content that modify a character’s base power in combat. Their significance to his overall power generally grows as he levels up. Here are some examples:

Skill Points or Talent Points. Each point increases character power by a percentage.

Item Modifiers in tons of RPGS. They get more numerous / significant at higher levels.

Materia in Final Fantasy VII. Players get more powerful Materia and can use more at once as they progress through the game.

(The impact of Materia on FFVII character power increases as they gain more slots and more powerful Materia.)

Players generally get to choose which power magnifiers they want to take to customize their character, and different classes use different power magnifiers. They key to balancing classes against each other is to ensure their available power magnifiers have equivalent effectiveness.

Power Magnifier Value as a Percentage of Base Power

Express the value of a power magnifier as a percentage of a character’s base power. “Percentage bonus to base power” is the universal unit to use to compare different types of bonuses.

Since all power modifiers are relative to base power, I like to define base power at any level as 1.0, for 100 percent. An unmodified level 1 character has a base power of 1.0, and so does an unmodified level 54 character. If a power magnifier increased a character’s effectiveness by 5 percent, it would have a value of 0.05.

To translate a bonus to “effectiveness,” calculate how much it increases the damage a character does in a fight before he is killed. So, a bonus that keeps him in a fight twice as long would double his effectiveness and have a value of 1.0 (because it is a bonus of 100 percent).

A particular power magnifier generally becomes available at a certain level, and is tuned to be appropriate for that level. For instance, see the “Affix Level” values in this chart of Diablo II item affixes. Determine its percentage value relative a character’s base stats at the level it is intended for. Some examples:

Percentage Damage Bonus

Imagine a skill that increases character melee damage by 1 percent. Since this is presumably a skill for melee characters, assume they always get its benefit; so it has a value of 0.01.

Conditional Damage Bonus

A sword has a modifier that gives it a 5 percent chance to deal 30 bonus damage on an attack. This is an average of 1.5 damage per attack. If base damage per attack is 100, then its value is 0.015.

Percentage Health Bonus

A 10 percent bonus to health increases the time that a character stays alive by 10 percent, thus increasing the damage he does in a fight by 10 percent, so it has a value of 0.1.

Armor Bonus

Say an armor bonus would improve a character’s damage resistance from taking 75 percent damage from an attack to taking 72 percent. This means he is taking 72 / 75 = 96 percent as much damage as he was before, multiplying his survival time by 1 / 0.96 = 1.04 times. Thus, the bonus value is 0.04.

Total Power

Each power magnifier that a character gets adds to his base effectiveness in combat. His total power is equal to the sum of his base power and all those magnifiers:

Total Power = Base Power + All Power Magnifiers

Power is relative to character level, so it’s more precise to write:

Total Power at Level X = Base Power at Level X + All Power Magnifiers at Level X

Remember, base power at any level is defined as 1.0. Thus, a level X character’s total power is the number of times more powerful he is than an unmodified level X character.

Planning a Progression of Total Power

Total power is what designers care about when tuning stats for content that opposes players, like monsters. As a designer, choose what value you want your game’s various power magnifiers to add to character effectiveness over the course of the game.

Systems can add power at different rates. A skill system might add 1 percent to total power each level. Unlocking a new ability might add a big chunk at a specific milestone. Players will focus most on content that has the biggest impact on their power, so assign systems value based on how central they are to your game design.

Here’s an example of how a total power progression could look. At level 1, no power magnifiers are in effect, so total power is equal to base power:

Total Power at Level 1 = 1.0

At level 10, the player has 9 skill points, each worth 0.01. He also has bonuses from item modifiers that increase his power by a total of 5 percent.

Total Power at Level 10 = 1.0 + 0.09 + 0.05 = 1.14

At level 25, the player now has 24 skill points, his item modifiers are now worth about 27 percent., and he’s unlocked a super power that increases power by another 20 percent:

Total Power at Level 25 = 1.0 + 0.24 + 0.27 + 0.2 = 1.71

In other words, a normal level 25 character is 1.71 times as powerful as a level 25 character with unmodified gear, no skill points spent, and who doesn’t use his super power. We can even chart out his total power over time:

In this chart, skills add a linear bonus to power, item modifiers add a gradual quadratic bonus, and ability unlocks add chunks of power every few levels. The purple line shows the total power of a character at each level, and that’s what monsters should be tuned against.

Solving for the Value of a Power Magnifier

Now that you’ve defined the expected power progression for characters in your game, you can look up the intended power value of any particular piece of content. For instance, if a level X character should get a 0.05 * X bonus in power from item modifiers, and is likely to have 10 modifiers on his equipment, then a level X modifier should increase power by 0.005 * X.

Once you know the intended power of a piece of content, do the math backwards to solve for parameter values that will give the content the intended power. Here are two examples:

Conditional Damage Bonus

A level 10 sword has a modifier that gives it a 5 percent chance to deal X bonus damage on an attack. Say the intended power of a level 10 modifier is 0.06, and the base damage per attack is 100. Thus, it should deal an average of 0.06 * 100 = 6 bonus damage per attack. Divide by the chance of dealing damage to find X. X = 6 / 0.05 = 120 damage.

Armor Bonus

A level 10 helmet has a modifier that increases armor. The intended power of a level 10 modifier is 0.06. For an armor bonus, this means the character should survive 1.06 times as long. Therefore, he should take 1 / 1.06 = 0.94 times as much damage with the modifier as without. Assuming a base character takes 75 percent damage from an attack, the modifier should be high enough to reduce damage taken to 0.94 * 75 = 70.5 percent.

Caveats / Where Doesn’t This Method Work?

This method is best suited for PvE combat in RPGs. Though it can be applied to other types of games, there are some game designs for which it’s simply not a good fit.

For example, it would be difficult to apply to action games where damage taken and received vary dramatically with player skill. Imagine an RPG where combat is based on regularly stunning or knocking away foes. It may not be possible to make sufficiently accurate value estimations in those games.

It can also be difficult to apply this method to game content whose value is not easily enumerated. Examples include bonuses to: Projectile weapon or spell range; Movement speed; Healing power;
Total mana.

In the case of bonuses like the above, you can either make a sophisticated mathematical model to get an accurate value estimate, or just guess and test, and go with what feels right. Either method can work great. (Source: Gamasutra)