Arianne is an engine to develop multiplayer online games like Stendhal
JavaScript framework to build game engines, games, emulators and apps
C/C++ , PHP, PYTHON, 3D ENGINES, CHROME NATIVE CLIENT
3D .NET engine for Windows, Linux, Mac
Create symmetric sprites: browse, save to PC, or store online
Free strategy browsergame engine.
Modular Gaming Open Source Persistent Browser Based Game Framework
Library for creating turn-based games with simultaneous moves.
Open source network game service
CLM for Joomla! 1.5 + 2.5
Moteur de jeux de rôles descripifs (RP) en PHP
Create your own online real-time browser-based MMO in your website
Ragnarok Cliente nativo para Gnu/Linux
Zap Engine
Atlarius is no longer under development.