SketchUp - 3D for Everyone
Unity - The multiplatform game creation tools for everyone.
Arena - Chess GUI Arena
Godot Engine - Feature-packed 2D and 3D open source game engine.
PTC Creo Sketch - Creo Sketch is an easy to use 2D CAD application for capturing and creating new 2D freehand concepts which is available on PCs, Macs, and iPads.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.