Gnomescroll - Gnomescroll is a multiplayer survival RPG in surreal environments.
Terraria - Dig, Fight, Build! The very world is at your fingertips as you fight for survival, fortune, and glory.
Clonk - Clonk is an entertaining, action-packed game of strategy, tactics, and skill.
Minecraft - A block-building game that allows you to create and explore entire worlds from scratch.
Epic Inventor - I have said a few times that Epic Inventor was inspired by Terraria.
Minetest - Minetest is a near-infinite-world block sandbox game and a game engine, inspired by InfiniMiner...