06 April 2011

[Literature] Game Balance ch6 - Situational balance

My notes from course 6 of the Game Balance class of Summer 2010, by Ian Schreiber.

If 10% of monsters are dragons, "double dmg to dragons" = 10% * 2dmg + 90% * 1dmg = 1.1dmg overall.
Situational balance = depends on the situation in the game; the cost is fixed cost, but the value changes depending on the situation. Ex: in DND, if atk + 1d20 >= AC then hit. Is +1atk (for player) balanced with +1def (for my opponent)?

  • yes if 1 vs 1 (+1 on each side)
  • no if enemies attack more often than player (because player will roll more often on AC than on atk) (eg 4 trash mobs vs one player)
  • no if player(s) attack(s) more often than enemies (more rolls on player's atk) (eg player group vs boss)

=> Level design tip: player should be outnumbered half of the time, and outnumber the enemies half of the time if atk and def have the same cost and value. This adds replay value ("I could start a new game with 20atk/80def instead of 50atk/50def")


In FPS, players usually have a close+strong+fast, a far+strong+slow and a far+weak+fast weapon. If player can switch weapons quickly, then it's as if the player had all of them at once. The overall price becomes the sum of all of these weapons, they should not be balanced individually.

A character/weapon is more versatile if it is able to handle more situations (Swiss-army knife). Examples:

  • RTS: archer very strong against flying creatures and very weak against footmen. If wizard is (a bit) strong against flying AND footmen, wizard is more versatile than archer.
  • FPS: knife = good in tight rooms VS snipers = good in large open-spaces VS machine gun = average on any map (= versatile weapon). Machine gun is the most valuable choice for players when they do not know which map is going to be played.

Solution against versatility: cost for switching can be time (it takes 5s to switch weapons), money, frequent weapon reload, etc. If switching is free, then player accumulates everything and uses each tool when he needs it. If inventory is limited, player will look for optimizations (eg only get fire and wind swords if you can only get 2 swords of the 4 elements). Balance depends on how fast player should be receiving new items.

  • fast: price = constant (but player earns more and more as he progresses, so player gets swords quickly)
  • faster and faster: "Since you’re such a good customer, you can have a 10% discount on all future swords."
  • slow: prices increase

Two kinds of versatility:

  • Ability of a single game object to be useful in different situations
  • Ability of the player to change between game objects (if this type of versatility increases, then the value of each object's versatility decreases)

Shadow costs

Object cost = resource cost (how much player buys it) + shadow cost (maintenance, etc.). Shadow costs can be sunk costs or opportunity costs.

Sunk cost

Sunk cost = pre-requisites/tech tree costs. Examples:

  • building a RTS unit may require buildings + techs. Building only 1 unit = lot of sunk cost, building many units = factored sunk cost
  • WoW tech tree: powerful ability now VS weak ability now opening VERY powerful ability later?
  • buying expensive shop discount card or a potion-making machine VS buying cheap potions repetitively?

Opportunity cost

Opportunity cost = how much versatility is reduced = when a choice prevents the player from taking another action later on. When an action adds constraint, how much is it as a cost? Examples:

  • Protection from Fire costs 10 G. Protection from Ice costs 10 G. How much costs Fire+Ice protection?
    • 10G if player knows opponents' atk ahead of time,
    • 20G if player can not know,
    • 15G if player can not know but can purchase the other one if you guessed wrong.
    Giving hints (eg if player is told about a red dragon, she expects fire) reduces the cost.
  • strong single-target VS weak AoE
  • Alternates: Situational objects that can be brought into play if needed, but the player isn’t forced to use them when suboptimal.
  • Metagame combo: not useful on its own, but useful if paired with something else (eg support class in MMO, building a CCG deck); the game should be balanced assuming optimal play, not average, because players will become good and play well anyway.
  • RPG multi-classing and 'either/or' choices: lvl 10 thief = lvl 10 warrior = lvl 7 thief-warrior. Cost = more than either but less than both.

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