The Core Gameplay Loop is the very heart of a game. It is arguably the single most important part of a game. It is a cycle of actions the game requires the player to perform over and over. Consider chess. In chess, the core gameplay loop is
1) Analyze the board 2) Make a move 3) Examine Opponent's move
In a Call of Duty game, the core gameplay loop is
1) Move strategically 2) Look for enemies 3) Shoot enemies
In Pac Man, the core gameplay loop is
1) Eat dots 2) Avoid ghosts
The core gameplay loop will be repeated often in a game, but is not necessarily a repetitive task. For example, in chess, your opponent may make a move you did not expect, or in a Call of Duty game, you may run out of ammo for your primary weapon and have to change your strategy to account for your change in weaponry. In Pac Man, a ghost may wander towards the dots you are trying to get to, forcing you to rethink your path.
Core gameplay loops can be simple or complex, but what is important is that they are enjoyable and variable. The player will spend the vast majority of their time in this loop, and so it is vital that it receives a high amount of refining.
Acosta, Keyvan, et al. "Core Gameplay Loop" 100
Principles of Game Design. Ed. Wendy Despain. Illus. Raymond Yuen. San
Francisco: New Riders, 2013. 70-71. Print.
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