Originally posted by magnificent moose:

The game does not have "official" servers. You have basically three options: you can play a single player game, or you can host a session for your friends, or you can setup a dedicated server if you have a spare computer that's always on. In the first two cases nothing will obviously happen while you're not playing. If you are running a dedicated server then things can happen while you're not there but I think it requires that at least someone is on the server.

Ok, thanks. Makes sense. I will probably want to play single a lot but then at certain time invite someone I know to come along and help out. Perhaps help them too on their server.