GemRB is a portable open-source implementation of the Infinity Engine
Arianne is an engine to develop multiplayer online games like Stendhal
2D Open Source MMORPG
An open source RPG Monster-fighting game
A sci-fi JRPG for Mac and Windows
plugin-based RPG manager in C++ and Qt5
full-blown GTA 3 -SA clone. Done in Game Maker. No missions though
Portable version of Phoenix Viewer 1.6
A RPG Text-Based Command Prompt Game by Takaya Sato
Final Fantasy like 3D Game