Totally awesome rendering, but how do I keep from dropping through the floor? I’m on a laptop+Chrome. The shift keys seem to be the only way to change elevation

Totally awesome rendering, but how do I keep from dropping through the floor? I’m on a laptop+Chrome. The shift keys seem to be the only way to change elevation and both go down. Would be nice if Q & E would go up down, since they’re in the locus of the WASD controls. Is this really ray tracing the glass bits? The way it turns on & off when passing through the glass surface hints at some hybrid shader tricks, perhaps?