Use the arrow keys (the down arrow key doesn't work in this simulation) to move your person around the environment. This simulation puts you in a randomly-generated environment with a black hole (which ironically shows up white) in its center. For reasons unknown you are in no way affected by the black hole; however, it can seriously mess up the direction of the light if you're looking in its direction.
I was bored. This is purely experimental--in fact there is a glitch (which I didn't notice until a brief period where I considered tracing the path of light on the map) where the black hole actually SPEEDS UP the light enough that it GOES RIGHT THROUGH THE WALLS without the computer registering that anything's wrong.