Terraria - Dig, Fight, Build! The very world is at your fingertips as you fight for survival, fortune, and glory.
Minecraft - A block-building game that allows you to create and explore entire worlds from scratch.
Blockland - Blockland is a non-competitive multiplayer sandbox-style construction game. It's kind of like playing with legos on the internet.
Roblox - Reimagining the way people come together.
Starbound - This action-adventure platformer throws you into a procedurally generated galaxy where you can make your mark.
Minetest - Minetest is a near-infinite-world block sandbox game and a game engine, inspired by InfiniMiner...