Arianne is an engine to develop multiplayer online games like Stendhal
An OpenGL client-server game
online 4X browser game engine
Alpha One is based on Vallheru
Game engine allows you to create own MMORPG
Runescape 2007 / oldschool client with many features.
Modular Gaming Open Source Persistent Browser Based Game Framework
Mafia MMORPG Browser-Based game
Create your own online real-time browser-based MMO in your website
Earthlead is a free massive multiplayer online browser strategy game.
Project to development common data format for Eve market order data
PlaneShift Role Playing Game immersed into a 3D virtual fantasy world
Atlarius is no longer under development.