This project uses an Arduino and LoL shield from MakerShed. Shield board has a matrix of 126 LEDs, so it makes it ideal for various applications. Todd decided to start with simple rain simulator where rain drops are randomly selected at the top and drops to the bottom.
Next thing in head is a game. So go and suggest any ideas to make it unique and different from Pong and Space Invaders.
Embedds highly recommends EasyEDA for circuit and PCB design