As mentioned below, I bought a metal Dance Dance Revolution pad for the navigation interface for the Infinicity:
I’ve got the pad controlling motion through the suburb demo. Stepping forward moves the viewpoint forward, stepping back produces backwards motion, and stepping to either side causes the camera to turn in that direction.
I’ve also added a splash screen- it alternates through three shots from the various pieces of the app (to be updated as the visuals improve) until a coin is inserted. Once a coin is inserted, the user is free to move around the space via the DDR pad. The time a quarter buys isn’t strictly limited, but if there is no motion on the part of the user for a set period, the app reverts to the splash screen until another quarter is inserted.