Originally Posted by GhanBuriGhan
Well, that at least would seem to have been taken care of by their friend matching strategy.

Presumably though you can play solo too, if you don't have friends online or just feel like it. The problem with this being that it's then necessary to scale the challenges in the game (which you'd also need to do for single player offline) according to numbers, or have NPC companions. I haven't seen these issues mentioned.