The Tiny JavaScript Game Engine That Can!
Free, open source game engine online
Full featured MUD server with all the trimmings.
Visual Basic 6 2D online adventure game engine
3D playground built on three.js and cannon.js
A cross-platform 2D game engine
A mobile game distributed server implemented using netty4.X
online 4X browser game engine
Java Client + JS/Canvas Server-Side System, with maintained Objects
Cross-platform 2D game engine
Free MMORPG Engine. Develop and host graphical browser-based games.