Physics Engine

A physics engine is the primary mechanism for the gameplay of a video game which comprises the algorithms for collision detection, gravity, motion, effects of these on the geometry. etcetera. It is responsible for determining the physical aspects of a game and those aspects' effect on the dynamics of the game.

Grand Theft Auto IV uses the Euphoria engine as its proprietary physics engine. This engine uses information on the human mucle and skeletal systems and the physics of the real world, combined with new software that uses more accurate techniques for collision detection to deliver more realistic movement than regular animations.