Scratch - Scratch is the programming language & online community where young people create stories, games, & animations.
Unity - The multiplatform game creation tools for everyone.
Blockly - Blockly is a library for building visual programming editors.
Godot Engine - Feature-packed 2D and 3D open source game engine.
EduBlocks - Making the Transition from Scratch to Python easier.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.