Powerful, mature open-source cross-platform game engine for Python
A retro game engine for Python
Open source clone of the Age of Empires II engine
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
A pure Go game engine
Free, open source game engine online
A refreshingly simple data-driven game engine built in Rust
3D game engine/framework in C, with Luajit and Python bindings now
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
Opensource crossplatform Fallout 2 game engine writen in C++ and SDL
Go 3D Game Engine
DOOM / Heretic / Hexen source port with enhanced graphics and UI
Python ctypes module for the Irrlicht Engine SDK
KlayGE is a cross-platform open source game engine
Scripting language of the hawk game engine
Browser game engine
The Lambda-Engine is a cross platform game engine.