List of first-person shooter engines

This is a sortable list of first-person shooter engines.

Specialized engines/engine middle-ware
Some features may be integrated into engines. For instance for trees and foliage a special "engine" is available, SpeedTree, that does just that (or could be integrated into general engines). The Euphoria character's 3D animating engine can be used independently but is integrated in the Rockstar Advanced Game Engine and the game Grand Theft Auto IV.