I was playing the classic 1P mode.
On game mechanics.. firstly, the objective is simple and easy to understand. But It seems that the control will get stuck for a while after you move 4 or 5 steps, and then the black-holes change place. After that you are allowed to move again, so the control does not feel responsive. Is this just me or is it because it's a web version? If it is indeed the game rule that you cannot move after a certain number of steps, it would be better if there's some animation to indicate that the space changing and the players cannot move.
For the appearance.. I am assuming that you're going for a trippy ambience simple game. Probably it's not worth mentioning, but more animation is needed, such as making the black-hole pulse or a quick interpolation on the player's movement will be effective.
Overall impression, I imagine this will be a fun party game when everyone is drunk (O.o) and waiting for something.