You can make it - Open Source MMORPG Platform
Fast and lightweight JavaScript game engine built on WebGL and glTF
Arianne is an engine to develop multiplayer online games like Stendhal
Game engine supporting many 3D/2D formats and graphic effects
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
The imaginary eight-bit machine
Modern 3D engine and IDE written using C# and C++.
Example code for creating a 2D platform game in Java.
An environment to develop games based on a rectangular board
Asphyre is a cross-platform framework for Delphi and FreePascal.
3D .NET engine for Windows, Linux, Mac
Single-/multi-player card game Mau Mau (similar to UNO®)
evolution for vegastrike SpaceSim/Combat/Trade game
Mahasona engine is an open source game engine.
Built to be ease of use, with no programming knowledge, Multi-platform
Cross platform Game Creation Software
Gives agents personality, moods, emotions and emotional attachments.
A generic 2D engine for any kind of game
Multi-threaded 2D Renderer licensed under the Mozilla Public License
Minecraft side viewed game made in Java
Kinect based controller.
A retro style video game engine for RPGs and adventure games.
Scriptable frontend for media applications.