Real Time Strategy game engine supporting early Westwood classics
Arianne is an engine to develop multiplayer online games like Stendhal
Java Settlers
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
A complete web framework to create online Fighting Fantasy adventures
X3D Prototypes for the SMUOS Component
Create symmetric sprites: browse, save to PC, or store online
Create your own online real-time browser-based MMO in your website
Make games with Lego-like building blocks