Didn't have anyone to play with, so I invented my own solo goal: finding all the little sound creatures and turning them off. This led to some mushroom jumping challenge, untill I found out that you could turn them off at a distance. In the end, I was left with an almost pitch-black level, stuck alone with only the silence of my soul to keep me company. Top marks for that little reflection on the crushing loneliness of playing multiplayer games alone :)