Terraria - Dig, Fight, Build! The very world is at your fingertips as you fight for survival, fortune, and glory.
Unity - The multiplatform game creation tools for everyone.
SimPhy - Interactive 2D & 3D Physics simulation software
Godot Engine - Feature-packed 2D and 3D open source game engine.
Roblox - Reimagining the way people come together.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.