Attrition

Type
Friction

Intent
Players actively steal or destroy resources of other players that they need for other actions in the game.

Also Known As
Multiplayer, destructive feedback

Motivation
By allowing players to directly steal or destroy each other’s resources, players can eliminate each other in a struggle for dominance.

Applicability
Use attrition when: strategic preferences and/or whims of the players.
 * You want to allow direct and strategic interaction between multiple players.
 * You want to introduce feedback into a system whose nature is determined by the

Structure


Participants
game.
 * Multiple players who have the same (or similar) mechanics and options.
 * A strength resource. A player who loses all his strength is eliminated from the
 * A special attack action that drains or steals the other player’s strength.

Collaborations
By performing attack actions, players can drain each other’s strength. Attacking may, or may not, cost strength to perform. If attacking doesn’t cost strength, it should require time to perform or involve some measure of skill or randomness. The balance between the attack costs, its effectiveness, and how beneficial the other actions in the game are determine the effectiveness of the attack and the dominance of the attrition pattern.

Consequences
Attrition introduces a lot of dynamism into a system because players directly control the measure of the destructive force applied to each other. Often, this introduces destructive feedback because the current state of a player will cause reactions by other players. Depending on the nature of the winning conditions and the current state of the game, this feedback might be negative when it stimulates players to act and conspire against the leader, but it also might cause positive feedback when players are stimulated to attack and eliminate weaker players.

Implementation
For attrition to work well, players should be required to invest some sort of resource in attacking that could also be spent otherwise. If they don’t have to make this investment, in a two-player game attrition simply becomes a race to destroy the opponent with few or no strategic choices. In a multiplayer game that facilitates social interaction between the players, attacking without investment works a little better because the players need to choose whom to attack.

It is quite common to implement attrition using two resources, life and energy, instead of just one, strength. Players use energy to perform actions and lose the game when they run out of life. When using these two resources, it is important that they be somehow related. Often, players are allowed to spend energy to gain more life. Sometimes the relationship between life and energy is implicit. For example, when a player must choose between spending energy or gaining life, there is an implicit link between the two because players generally cannot do both at the same time.

In a two-player version of attrition, the game must include other actions, and games for more than two players often allow other actions that the players can perform. Most of the time these actions constitute some sort of production mechanism for strength, which increases the effectiveness the players’ defensive or offensive capabilities (and thus elaborates the attrition pattern to an arms race pattern). Most real-time strategy games include all these options, often with multiple variants for each.

The winning conditions and effects of eliminating another player have a big impact on the attrition pattern. The winning condition does not need to be elimination, however. Players might score points, or reach a particular goal outside the attrition pattern, which automatically widens the number of strategies available. When there is a bonus for attacking or eliminating players, the pattern can be made to stimulate the elimination of weaker players.

Examples
Almost all strategy game implement some sort of attrition as it is often an important goal to eliminate other players in this type of games. The SimWar provides a good example.

The trading card game Magic: The Gathering implements an elaborate version of the attrition pattern. The diagram below presents this implementation, although it shows the details from the perspective of a single player only.



In Magic: The Gathering, players can play one card every turn. These cards allow players to add lands, summon creatures, cast spells to heal, or deal direct damage to their opponent or their opponent’s creatures. But all actions except playing lands cost mana (magical energy). The more mana players have, the more they can spend each turn and the more powerful actions they can play. Creatures will fight other creatures, and when there are no more enemy creatures, they will damage the opponent directly. Players who lose all their life points are eliminated from the game. Magic: The Gathering is an example of a game that implements attrition using separate resources for life and energy (or in this case, life and mana).

The different gameplay options in Magic: The Gathering illustrate how attrition can work differently. Direct damage briefly triggers a drain. As its name implies, it is fast and direct. On the other hand, summoning creatures activates a permanent drain on the opponent’s creatures and life. The effects usually are not as powerful as direct damage, but because they accumulate over time, they can be quite devastating. The cards in the player’s hand determine which options are available to him and exactly how powerful those options are. Because players build their own decks from a large collection of cards, deck building is an important aspect of Magic: The Gathering.

The most obvious way to implement attrition is in a symmetrical game. However, many single-player games and even certain types of multiplayer games use asymmetrical attrition. An example of asymmetrical attrition can be found in the board game Space Hulk in which one player, controlling a handful of space marines, tries to accomplish a mission while the other player, controlling an unlimited supply of alien “genestealers,” tries to prevent that. The genestealer player tries to reduce the number of space marines to stop them from accomplishing their goals and wins when the genestealers have destroyed enough space marines. The space marine player usually cannot win by destroying genestealers but must keep the number of genestealers under control to survive, because the genestealers become more effective as their numbers grow. Figure B.12 is a rough illustration of the mechanics in Space Hulk.



Related Patterns
nearly always negative.
 * Attrition works well with any sort of engine pattern. Trade can be used as an alternative form of multiplayer feedback that is constructive instead of destructive and is
 * Attrition elaborates the Dynamic Friction pattern.
 * Attrition can be elaborated by the Arms Race and Worker Placement patterns.