GemRB is a portable open-source implementation of the Infinity Engine
An isometric arcade-style game of skill, puzzles and exploration
SDL based generic 2D game engine
Javascript library for making tile based games
a UCI chess engine
2D Game Engine
A cross platform Lua based game engine
Free and Open Game Programming Language for Windows and GNU/Linux
Real-time RPG for PC/tablet/phone; multiple quests and random dungeons
scriptable game engine with built-in support for 2D graphics and sound
Multi-platform game engine similar to old Megaman with a stage editor
Mahasona engine is an open source game engine.
Built to be ease of use, with no programming knowledge, Multi-platform
Open source, moddable game engine for the "Polygon Love 2" game
Java game engine for shoot 'em ups, using Java2D.
Framework for a graphical point and click adventure game in Java
Cross-platform 2D game engine