Desktop/Android/HTML5/iOS Java game development framework
Lightweight, facility, high performance golang based game server
Framework for creating human behaviour experiments in Unity
scriptable game engine with built-in support for 2D graphics and sound
Lightweight framework for old-school RPG GUI in web!
Multi-Language Wrapper Collection for the Irrlicht Engine
Superseded by OpenTK: https://sourceforge.net/projects/opentk/