Thank you very much for the feedback. I've been busy jotting down notes on everyone's feedback, and I've got plenty of stuff to improve. I agree that having some sort of goal or obstacle would be good to give the player a bit more direction, something to work towards.
Another thing I had considered was to implement some sort of leaderboard and have people try to beat each other's scores (currently the room is procedurally generated every time you start a new game, but it could be easily modified so that players can provide a specific seed if one turns out to be particularly challenging or interesting).
Now I just need to find the time to implement all of these ideas. =)