Magic Another Game Engine
Arianne is an engine to develop multiplayer online games like Stendhal
A Forge mod that implements SpongeAPI
RelaxChess, chess game that makes no search futher needed for a wow
A simple 2D-Chess
GaPla is a free games Platform written in Java
Cross platform administration tool for Source Engine dedicated servers
An OpenSource (C# .NET) TeamPlay Environment.
A multiplayer Blackjack game which works over the internet
War of Respect is an online turn-based MMORPG in 2D-anime style.
Multi-user whiteboard emphasizing simplicity.