GDevelop - GDevelop is an open-source game making software designed to be used by everyone.
Lumix Engine - Open source 3D game designer and engine written in C++.
Project Anarchy - Project Anarchy is a complete end to end game engine and state-of-the-art toolset for mobile.
Grit Game Engine - The Grit Game Engine is an MIT-Licensed Open Source Game Engine that is highly scriptable via Lua.
Struckd - 3D Game Creator - Struckd is the next-generation gaming platform for user created content where people of all ages...
MOS - Lightweight game engine.