Starwhal
I tried introducing Starwhal to handful of acquaintences, and every single one of their first reactions was how odd the game controls. And control it does-- very sensitively. It's one of those gimmicks that the mainstream audience will probably never appreciate. And it's too bad because there is a great game here underneath..
You swim around frantically and try stabbing your opponents in the heart with your nose. It's tempting to dismiss as some distracting children's game, but kids might have a hard time getting used to the precision control it takes to guide your swordfish.
If you have enough patience (which is like 8 minutes these days) then you can probably adapt and will get some milage out of Starwhal. It's cool if you can find another non-CPU to join you. Oh and the music is pretty good too. In fact, it's better than OK.