WASD to move 1 - sphere 2 - torus 3 - Klein bottle 4 - projective plane Space to trace your path e show you how distant things are for you. It can be very laggy. q decides the resolution and distance that will be traced. Both are measured in numbers, and 100 is the default for both. This is made to give a very rough idea of distances in different maps.
Credit & detailed explanation: