Odamex is a free, cross-platform, modern client-server Doom engine
A free 3d game for PC that does not limit the player. Fight,Build,Gain
Visual Basic 6 2D online adventure game engine
0 A.D. is a free, open-source, cross-platform real-time strategy game.
mGSTEP port of the Cube game engine
FreeCS is a free-software reimplementation of Counter-Strike 1.5.
A fun realistic multiplayer free-and-open-source first-person-shooter!
An open-source, multiplayer fps based on Cube 2 Engine.
C/C++ , PHP, PYTHON, 3D ENGINES, CHROME NATIVE CLIENT
starrydb is game server engine
Clone of Urban Assault with new Graphics.
A collection of all maps and games made for the TripleA game engine
Java decentralized cross-platform network multiplayer game engine
Free strategy browsergame engine.
Your death sentence awaits...
3D FPS Digital Paintball 3 Multiplayer Online Game
Library for creating turn-based games with simultaneous moves.
Action-packed local multiplayer game
A free open source Android version of Caravan
Gameserver Installer/Startscript for HL1 and HL2 Games
Open Source Virtual World and MMOG Development Platform
Mighty 34th century meka action from TeamXbow
A Dungeons & Dragons Miniature Game.