A game engine powered by python and panda3d
High performance UI layout library in C
Godot Minimal Theme
3D game engine/framework in C, with Luajit and Python bindings now
A modern, cross-platform Quake game engine based on FitzQuake.
GemRB is a portable open-source implementation of the Infinity Engine
Game engine supporting many 3D/2D formats and graphic effects
C++ lightweight cross-platform game engine
A game engine for console based text games
State Management and Multiplayer Networking for Turn-Based Games
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
DOOM / Heretic / Hexen source port with enhanced graphics and UI
scriptable game engine with built-in support for 2D graphics and sound
Flexible and easy-to-use 2d game engine
A 3D game engine in java.
Open source, moddable game engine for the "Polygon Love 2" game
Game engine supporting many 3D/2D formats and graphic effects
The Lambda-Engine is a cross platform game engine.