Minetest - Minetest is a near-infinite-world block sandbox game and a game engine, inspired by InfiniMiner...
Terraria - Dig, Fight, Build! The very world is at your fingertips as you fight for survival, fortune, and glory.
Roblox - Reimagining the way people come together.
SimPhy - Interactive 2D & 3D Physics simulation software
Physion - Physics Simulation Sandbox
Lamecraft - Minecraft clone for Playstation Portable (PSP)