Previously known as the Quake II engine, id Tech 2 is based on the Quake Engine, and features some enhancements such as colored lighting and a new model format. Game code is now written in C and loaded from a DLL, in place of the original Quake engine's QuakeC scripting language.
Commercial titles that use this engine (note that many of these use a combination of id Tech 2 and the Quake Engine):