Unity - The multiplatform game creation tools for everyone.
Kodu Game Lab - Kodu lets kids create games on the PC and XBox via a simple visual programming language.
Struckd - 3D Game Creator - Struckd is the next-generation gaming platform for user created content where people of all ages...
Reality Factory - Reality Factory is a free suite of game development tools for building 3D games.
Scroller Game Creator - Create your scroller shooter game
Limon Engine - Limon is a multi platform 3D game engine mainly focusing on first person games.