"Wack-a-mole" meets "Twister" with Sifteo cubes as input!!
Setup: There is a PC which is just a visual output device (and runs the game). The game itself is a "whack a mole" type game, where enemies appear and disappear on a 3x3 grid:
  
  
  
The Sifteo cubes are mostly for input. Initially, the cubes are set up in the following manner (or similar):
[R]   
Each cube has an initial number it represents (which corresponds to the same number on the grid). To hit an enemy, you must press on the cube. But, you'll notice there aren't enough cubes to cover the entire grid. That's where the [R], or reset cube, comes in. If an enemy appeared on , then, for example, the player would need to:
1. Grab , and "neighbor" it or tap it to [R]. This would cause  to reset to a neutral value [N].
[R] [N]  
2. The player would take the new [N] and neighbor it to  at the bottom. [N] would now become .
[R]  
3. The player would press  to hit the enemy... IF the enemy hasn't disappeared by then!!
It's a simple game with multiple knobs for difficulty.
Coming Soon: gameplay explanation via a video or slideshow