The DiamondTouch table is a touch-sensitive input device that allows several users to interact with a program at the same time and do so using their hands. We describe our exploration of the capabilities and limitations of the DiamondTouch by focusing on TetraTetris, one of the first nontrivial applications written specifcally for the DiamondTouch hardware. TetraTetris is a multi-player game, loosely based on the popular game Tetris, in which players use their hands to manipulate objects moving around on the table; it illustrates some of the table's key advantages and drawbacks by comparison with conventional input hardware. In this paper we describe the DiamondTouch hardware, the rules of TetraTetris, the problems we encountered implementing it, and what TetraTetris can show us about the future of input devices like the table.