GemRB is a portable open-source implementation of the Infinity Engine
Game engine supporting many 3D/2D formats and graphic effects
A fork of Chocolate Doom with small Quality of Life enhancements
A fork of dhewm3 with an emphasis on modernisation and vanilla Doom 3
DOOM / Heretic / Hexen source port with enhanced graphics and UI
A cross platform Lua based game engine
Low-Level Game Engine for Retro Platforms
online 4X browser game engine
Paintown is a 2d fighting game engine.