The video game development team member plans the gameplay, rules, and structure of a game; may also work on the game's narrative:

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The game designer is responsible for planning the gameplay, rules, and structure of a video game, and they may also contribute to the game's story or narrative. This role involves conceptualizing the game's core mechanics and how it will be played, which distinguishes it from the more specialized roles of artists, who create visual content, programmers, who write the code, and level designers, who design the individual levels or environments within the game.

The Video Game Development Team Member Plans the Gameplay, Rules