For those of you interested in making your own custom DIY RGB LED Tetris game, take a look at the work done by Stanislav Ponomarev, pretty darn impressive. I have always thought of putting one of these in my future coffee tables so my guests can enjoy some retro-gaming while they relax.
Principle of operation is quite simple. Up-counter is responsible for keeping track of which row is currently being shown, 4-to-16 decoder converts 4-bit binary number from up-counter into 16 different lines. The decoder I have outputs LOW for the current input value, so I had to pass all 16 lines from decoder through the inverters to
transistors, which just allow a higher current get to the LEDs. Without transistors LEDs show much dimmer and the whole row can not show white.