1. "Mariana Trench" - a deep sea adventure (and no, the Captain is not smoking dope).
2. "HIT World" - (Short for Hole In The World) - A giant sink hole swallows up pinball machines and you need to save them from extinction.
3. "Mission to Mars" - Space pilgrims ready to colonize the red planet.
I think that un-themed pins would give a lot of room for creativity and imagination which themed pins restrict.