subgame — English Dictionary

Noun

1. A subset of a game that can be considered a game in its own right.

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   A subgame is a piece of a game—the piece that remains to be played beginning at any point at which the complete history of the game thus far is common knowledge among the players.

2. A minor or incidental game within a larger video game; a minigame.

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   There was a subgame that was very well-recieved ^([sic]) in the previous Paper Mario RPG [Paper Mario: The Thousand-Year Door], where you would play through this side-scrolling stage as a gigantic Bowser.