PG Music has announced that Pitch Invasion, a new musical game for iPhone, iPod Touch, and iPad, is now available from the iTunes App Store. It's free for a a limited time.

Based on old-style classic arcade games, "aliens" descend upon your home planet, intent on destroying your prized collection of musical instruments. It's your job to blast them out of the sky by recognizing the pitch that they are playing, and playing that pitch yourself before they reach the ground. If they reach the ground, one of your 15 musical instruments is destroyed. Once your instruments are all destroyed, it's game over. As you blast the aliens, you can move up to harder, faster levels.