Xash3D FWGS engine
The ioquake3 community effort to continue supporting/developing id's
Orx: Portable Game Engine
Game engine to build text adventures.
An authentic Rise of The Triad Dark War source port
Cross-platform 2D and 3D game engine
Low-Level Game Engine for Retro Platforms
creator : Nikola Lukic about : Visual JS 2d canvas multiplatform game
A basic 3D environment with a first-person POV
A Simple Game Engine
Reference implementation for the Doom game engine.