Robocode is a programming tank game for Java
A companion for your LOTRO activities
Arianne is an engine to develop multiplayer online games like Stendhal
Java Settlers
JamochaMUD is a Java MUD/MUCK client.
A graphical frontend for PbeM like Eressea
Java library to BiDiB (see http://www.bidib.org/)
A Java client for mangband.
Project to create a Java based SCUMM engine.
A Twitch Chat Client
Java decentralized cross-platform network multiplayer game engine
Cross platform administration tool for Source Engine dedicated servers
The original Xivio.com World Server Core