Kodu Game Lab - Kodu lets kids create games on the PC and XBox via a simple visual programming language.
Godot Engine - Feature-packed 2D and 3D open source game engine.
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!
GDevelop - GDevelop is an open-source game making software designed to be used by everyone.
Flowlab - Flowlab is an online game creator. Make your own games to share with friends.
Unity - The multiplatform game creation tools for everyone.