SparkFun team have made a huge interactive Tetris game. This is really impressive piece of art made of 16 Atmega8 microcontrollers, 720 LEDs and 240 buttons. Game can be controlled by touching buttons directly on frame(similar to touch screen).
The Tetris board is 10×20 cells and each cell lights up 1 of 7 different block colors. Separate button pads are 4×4 and there are 15 of them, so total array is of 12×20 buttons. There is RGB LED placed behind each button so it is possible to light any button with any color. Can imagine what processing power is needed to update all picture and read all button state. This is why whole project was break up in pieces of 4×4 button pads with separate microcontrollers accessed via SPI interface. Project is really challenging but satisfaction is 100% guaranteed. They provide all schematics and firmwares if somebody wants to give a try.