Pitch Invasion utilizes old-style arcade games for ear training.
These aliens will try to descend upon earth and they aren't just planning on vacationing - they want to destroy musical instruments!
Your duty is to blow them to bits before they land by recognizing the pitch they are giving off and playing them yourself before they reach the ground. Everytime the aliens drop in on you, they destroy one of your precious 15 instruments.
This is a fun and retro-ish way of getting your ear in tune and in shape.