See, the thing about IR tracking is that it's really only fun and useful in a situation where you're stationary, and are just tilting your head around; something like a flight simulator, to look around the cockpit, for instance. It's really, really not useful at all in FPSes, and just makes things difficult, cumbersome, and game-breakingly imprecise.
And the idea of walking around a room as input control for a game, sorry, but it's just totally impractical as a control method. Okay, so I'm playing Metroid Prime by walking around my room. I've got a few feet I can move in any direction...and then what? It's really not terribly useful at all.