I'd take quite a different approach,.... for one, I'd make it a boot with some ankle support, because the idea of something allowing my foot to slide says twisted ankle to me. Second, I'd replace the rollers and wheels with a bed of trackballs, so the boot can move in full 2D, and sweep and slide, simple pressure sensors will actually do the opposite of what usually happens, when there's pressure put down on the boot, the trackballs will unlock and slide to prevent IRL movement and signal In Game Movement, when it's lifted they will lock, allowing the other boot to move.
Surely though some restraint of the torso is needed still, to react against, or people are going to fall over?