Cocos simplifies game creation and distribution with Cocos Creator
Free game engine for development of desktop, mobile, and web games
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
FlightGear Flight Simulator: free open-source multiplatform flight sim
A planetarium software that shows a 3D simulation of the night sky
3D modeler, 3D game maker, 3D demo maker
Maze creation, solving, exploration, and analysis
GameServer is a sophisticated, game server designed for online games
Combat Flight Simulator for LINUX. WW2. Network and VOIP. Open-source.
MIT Licensed Open Source version of Torque3D from GarageGames
C/C++ , PHP, PYTHON, 3D ENGINES, CHROME NATIVE CLIENT
3D Game engine
3D FPS Digital Paintball 3 Multiplayer Online Game
SuperWikia: The Runtime/Realtime Environment for Codesmiths
3D Web UI, Embed Web and Flash in 3D Games, based on WebKit
3D Engine technology with partial tools developing kit.