Kodu Game Lab - Kodu lets kids create games on the PC and XBox via a simple visual programming language.
Unity - The multiplatform game creation tools for everyone.
Ceilfire - Ceilfire is an online game maker for creating HTML5 games and sharing game assets. Make play and share games directly in your browser! Make Your Own Game!
Struckd - 3D Game Creator - Struckd is the next-generation gaming platform for user created content where people of all ages...
Flowlab - Flowlab is an online game creator. Make your own games to share with friends.
Reality Factory - Reality Factory is a free suite of game development tools for building 3D games.