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