Clonk Rage - Real-time multiplayer game. Players can download more than 47475 maps at ccan.de
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.
The Blockheads - Night is falling and your blockhead is freezing.
Gnomescroll - Gnomescroll is a multiplayer survival RPG in surreal environments.
Epic Inventor - I have said a few times that Epic Inventor was inspired by Terraria.