Open 3D Engine (O3DE) is an Apache 2.0-licensed multi-platform 3D
Svelto ECS C# Entity Component System
A modern, cross-platform Quake game engine based on FitzQuake.
GemRB is a portable open-source implementation of the Infinity Engine
Orx: Portable Game Engine
SDL based generic 2D game engine
C++ lightweight cross-platform game engine
a UCI chess engine
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
DOOM / Heretic / Hexen source port with enhanced graphics and UI
mGSTEP port of the Cube game engine
KlayGE is a cross-platform open source game engine
Opensource Game Studio
Portable game engine with main focus on point-and-click adventures
An Adventure Game Engine
The second demo of my game engine.