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Uses two-dimensional "sprites", 2D images created and used on a flat plane, as opposed to the three-dimensional models or environments found in 3D games.

Games that can be played by more than one player, either locally or online.

Science-fiction. Commonly including things like aliens, advanced technology, and settings of outer space or distant planets. 

Games where the primary goal is keeping the player character alive under harsh circumstances such as dwindling resources or a hostile environment.