Engine

RIOT Civil Unrest is powered by the Unity engine and emulates a 2D retro look, but the scene is actually 3D. This gives the Developers more control over a more realistic lighting, physics and effects.

Crowd physics
Developers of the game used the Unity 3D crowd physics. It later became apparent that it wasn’t going to work for with large crowds and got replaced by Trigghy’s crowd physics, created by developer Trigghy.