The Dark Engine is the computer game engine used for the Looking Glass Studios games Thief: The Dark Project (1998), Thief II: The Metal Age (2000), and the Looking Glass/Irrational Games title System Shock 2 (1999).
Dark Engine, it may be old the games that were made for it are still very much playable and fun. Many great memories are built on this engine.
The classic engine behind Thief: The Dark Project and Thief: The Metal Age. Features better lighting, sound propagation, and AI than any game before it.
NewDark has modernized the engine: Ttlg.com