for FPS, I'd be interested if you could recreate the WSAD setup for moving with foot pedals? Your feet can be quite dexterious, just most of us never use them for more than walking. I'm thinking something like using the whole foot to control the buttons, not toes. Something sort of like how a kick drum works maybe, but with two degrees of freedom for the heel and toe?

edit: I mean, hell, dance dance revolution sort of does that already and the savants that play that can do crazy speed with their feet.

There was a girl at my school a couple of years above me who was born with no arms. She could write reasonably well, feed herself, etc. via her feet by using her toes like fingers. I was always impressed with just how able she was. She ended up getting her drivers license and everything with a steering wheel that she can use with her feet.