GemRB is a portable open-source implementation of the Infinity Engine
Game engine to build text adventures.
Arianne is an engine to develop multiplayer online games like Stendhal
General Purpose Engine for Graphic Adventures.
Cross-breeding a 3D FPS with a fantasy RPG in the world of Hexen
Action RPG that's easy to mod
Real-time RPG for PC/tablet/phone; multiple quests and random dungeons
A fantasy RPG.
Processes dialogue text files exported by the Bethesda Softworks SDK
A space race game in the style of A Dark Room
PvP, MUD RPG.
3D urban environment renderer : browser-app ; as well as a GTA clone
plugin-based RPG manager in C++ and Qt5