Common Fate Principle

The Common Fate Principle is where elements in motion can be grouped together depending on what direction they are moving in. Games commonly use this principle in their enemy and obstacle structure, where their movements get the player's attention, and the player makes an informed decision based on their movement. The player first groups the moving enemies and obstacles into groups based on their motion, and dedicates some of their attention span budget on to those groups.

Good Example of applied principle

Below showcases a good example of how the Common Fate principle is displayed in games that use it primarily for their obstacle structure. In the game, Crossy Road, the theme of the game is to move the crossing animal across rivers and roads safely without being hit by the moving cars and dragged away by the floating logs. As part of the core gameplay, the player has to observe their surroundings to make timed decisions on where and when to move forward. The player dedicates some of their attention span to both east and west given that the obstacles only move from and to those directions.

Bad Example of applied principle

Below showcases a bad example of how the Common Fate principle is displayed in games that use it primarily for their obstacle structure. In Asteroids, the theme of the game is to guide the spaceship in the asteroid field, and prevent it from getting destroyed by incoming asteroids and alien spaceships. The player is capable of moving their ship and shooting projectiles as ways of dealing with the obstacles, but there is too much randomness in the directions they come from on screen. Due to this observation, the player has difficulty distinguishing and forming groups of the obstacles based on their motion and direction, which overloads their attention span budget.