Terraria - Dig, Fight, Build! The very world is at your fingertips as you fight for survival, fortune, and glory.
SimPhy - Interactive 2D & 3D Physics simulation software
Starbound - This action-adventure platformer throws you into a procedurally generated galaxy where you can make your mark.
Physion - Physics Simulation Sandbox
Dig or Die - Dig or Die is a sandbox action/strategy game; explore, fight, craft, and build your defenses!
Roblox - Reimagining the way people come together.