dhewm 3 main repository
GemRB is a portable open-source implementation of the Infinity Engine
Black Myth Wukong, Black Myth Wukong PC, Black Myth Wukong Review
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
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
2D physics engine for games
cross-platform 2d game engine