Orthogonal Differentiation

Differences in abilities of game entities that are in type rather than in value.

One of the uses of many game pieces or units in a game is to provide players with different types of abilities. When the abilities and functionality of these are not only quantitative but qualitative the game has Orthogonal Unit Differentiation. This give the different game pieces additional value since they represent the only ways for players to perform certain actions. Not all or many aspects of a units needs to be unique, often it is sufficient that a single ability of a unit is radically different from other units for it to have special gameplay value. In team games, the differentiation may actually be between players so that each player has unique abilities.

Examples

The pieces in Chess have different types of movement rules, giving them different gameplay value and giving the game Orthogonal Differentiation.

Real-time games such as the Age of Empires series and the Command & Conquer series are based around producing and making best use of a wide variety of units. Although few units have unique abilities, such as the converting ability of priests, many do have abilities that are only shared by a few other types of units and define one dimensional in the range of unit abilities in the game.

Using the pattern

Orthogonal Differentiation is used in games either to provide more gameplay without increasing production costs or create more Complex Gameplay, or both. The difference in functional abilities can either exists between different game entities under the same player's control or between those of different players' control. An alternative is to have Orthogonal Differentiation between Enemies. It is achieved through Asymmetric Abilities between Characters or Units. However, Asymmetric Abilities is not enough since the differences need to be in type rather than in degree. Although Privileged Abilities guarantees important differences in Abilities, New or Improved Abilities can also provide Competence Areas; even Ability Losses and Decreased Abilities can be used for this.

Typical areas where Orthogonal Differentiation is used include the ways to do Damage, availability of Skills and Combos, effects of Fog of War, and differences in how Movement can be done due to Privileged Movement.

Consequences

Orthogonal Differentiation provides more Varied Gameplay for a game compared to one with the same amount of Characters or Units but without distinct differences in Abilities. The difference and the added importance individual game entities may have give rise to Complex Gameplay but also Replayability. When players have control over the game entities with Orthogonal Differentiation of Abilities, making full use of the different Abilities promote Stimulated Planning. In games with Teams and Characters, Orthogonal Differentiation makes the possibility of creating Team Combos likely and through this Team Strategy Identification as well.

The unique abilities required by Orthogonal Differentiation makes it difficult to combine with Symmetry on the same level of game design. However, they can be combined by treating the differentiated units as a set and have the same sets for all players or all teams.

Relations

Can Instantiate

Complex Gameplay, Replayability, Stimulated Planning, Varied Gameplay

with Teams and Characters

Team Combos, Team Strategy Identification

Can Modulate

Characters, Enemies, Units

Can Be Instantiated By

Asymmetric Abilities, Competence Areas

Can Be Modulated By

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Possible Closure Effects

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Potentially Conflicting With

Symmetry

History

An updated version of the pattern Orthogonal Unit Differentiation that was part of the original collection in the book Patterns in Game Design. The concept was first introduced by Harvey Smith to game developers at a presentation at GDC 2003, and the presentation is available online.

Acknowledgements

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