The game engine for everyone
A MUD client for Android, iOS, Linux, Mac OS X and Windows
Source of Mana is a unique 2D MMORPG
Free, open source game engine online
Virtual paper folding program
Godot is a fully featured, open source, MIT licensed, game engine.
Two projects in one so far: to learn foreign words and read books
TurboSphere is an easy to learn and powerful JS based game engine.
To create an open source and openly developed mmorpg
Constraint Logic can solve word logic puzzles.