GemRB is a portable open-source implementation of the Infinity Engine
Arianne is an engine to develop multiplayer online games like Stendhal
A complete web framework to create online Fighting Fantasy adventures
3D urban environment renderer : browser-app ; as well as a GTA clone
plugin-based RPG manager in C++ and Qt5
Amber Crux is a 2D graphical adventure game.
A 2D Adventure Game & Engine
Role Playing Game Engine
Cross-platform port of Arx Fatalis, a first-person role-playing game
An Action Role-Playing Game
A Dungeons & Dragons Miniature Game.
The SCND Genesis: Legends
Free MMORPG Engine. Develop and host graphical browser-based games.