Previously called the "QUAKE 3 Engine" and one of the most successful licensed engines in history, id Tech 3 was the engine used to create games such as Quake II Arena, Return to Castle Wolfenstein and Soldier of Fortune II: Double Helix. id Tech 3 introduced shaders, curved surfaces, 32-bit color, special effects, bleeding-edge networking and super-smooth speedy hardware rendering.
An extremely well done engine. Games like Call of Duty, Medal of Honor and Return to Castle Wolfenstein are impressive, sadly they have a very small modding community compared to Id's previous engine, Id Tech 2. Truly an awesome engine, much better than his predecessors.