irrlicht - This caused the Irrlicht homepage and forum to work badly. Over the last days most things started working again – except the forum continues to be broken. Old posts can be read but everything else is currently not working.
Lumix Engine - Open source 3D game designer and engine written in C++.
Unity - The multiplatform game creation tools for everyone.
Grit Game Engine - The Grit Game Engine is an MIT-Licensed Open Source Game Engine that is highly scriptable via Lua.
Godot Engine - Feature-packed 2D and 3D open source game engine.
MOS - Lightweight game engine.