Many games have events that make players' future actions have less effect, or less chance of succeeding, than they originally had. These Decreased Abilities can be the consequences of running out of Resources or being affected by hostile actions but require players to use the abilities more efficiently to reach the same level of effect as previously.
Example: Each point of damage received in RoboRally gives the player one card less at the beginning of each turn. As these cards are used to program a robot's movement, the reduction in number of cards effectively reduces the player's ability to control the robot.
Example: Being hit by an ice cube or polygon ball weapon in the Monkey Race 2 party game in Super Monkey Ball 2 significantly reduces players' top speed and ability to steer.
Instantiating Decreased Abilities can easily be done by changing the values in the game state that are part of the evaluation functions of an action. Typically, this is motivated by changes in Skills of Characters or Units. An indirect way of achieving Decreased Abilities is to require use of Limited Resources, and maybe Non-Renewable Resources, so that players have to make Risk/Reward choices of whether to use the action. This limits the Freedom of Choice when the players can use the actions. Reducing the amount of Resources a player can access or store is another way to combine Decreased Abilities with Limited Resources.
Decreased Abilities are often used as Penalties to affect Player Balance. When the effect of this needs to be modulated, Time Limits of the decrease or complementing Improved Abilities in other areas can be used to achieve a Balancing Effect.
A common place for Decreased Abilities to occur in gameplay is as the consequences of Player Killing, either represented through the loss of Tools or experience.
Decreased Abilities are Penalties that affect players' Perceived Chance to Succeed. If an ability is decreased so much that the perceive chance of success to achieve a goal by using it becomes nothing, any Illusion of Influence due to the action is lost. If the chance actually is nil, the Decreased Ability can be seen as an Ability Loss and is in conflict with providing players with a Perceived Chance to Succeed. Unlike Ability Loss, Decreased Abilities can be used to affect the Right Level of Difficulty by raising it while retaining the Right Level of Complexity.
Decreased Abilities can be used to negatively define Orthogonal Unit Differentiation. This kind of differentiation typical is an emergent feature due to different levels of Damage or depletion of Resources between Units or players in a team.
Instantiates: Penalties
Modulates: Units, Player Balance, Risk/Reward, Right Level of Difficulty, Perceived Chance to Succeed, Characters, Skills, Orthogonal Unit Differentiation, Player Killing, Limited Resources, Right Level of Complexity, Improved Abilities
Instantiated by: Non-Renewable Resources, Limited Resources
Modulated by: Time Limits, Improved Abilities, Balancing Effects
Potentially conflicting with: Illusion of Influence, Perceived Chance to Succeed, Freedom of Choice