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!
Godot Engine - Feature-packed 2D and 3D open source game engine.
Flowlab - Flowlab is an online game creator. Make your own games to share with friends.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.