Pretending to pretend to play a musical instrument, only slightly below DJ Hero.
And I agree with Roph, how far is too far when you plan on stripping down controls? I'd hate to play any game on Natal. Interacting with a physical medium makes the experience more realistic...and easier, this just removes functionality.
Irock is right too, if it's done well it makes the gameplay all that much better.
Ok, I'll say it: sex games.
This should really be on the PSP then.