Open source clone of the Age of Empires II engine
Powerful, mature open-source cross-platform game engine for Python
3D game engine/framework in C, with Luajit and Python bindings now
A game engine powered by python and panda3d
A retro game engine for Python
An OpenGL RTS game engine written in C
Pycraft is an open-source, OpenGL based game made in Python
Free, open source game engine online
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
GemRB is a portable open-source implementation of the Infinity Engine
A cell-based puzzle game featuring classic and completely new puzzles
A game engine for console based text games
Urho3D Game engine
Python ctypes module for the Irrlicht Engine SDK
DOOM / Heretic / Hexen source port with enhanced graphics and UI
A cross-platform 2D game engine
KlayGE is a cross-platform open source game engine
Simple and low-consumption Java 2D Game Engine
Open source, moddable game engine for the "Polygon Love 2" game
Scripting language of the hawk game engine