Oh what a pain that is. We regularly play stuff like Settlers IV, Civ V, etc, which allow you to not only play offline, but on your own network, without having to rely on the internet. Not everyone in the UK has access to a high speed internet connection, in truth, I am lucky when I can get 10mbps.
Also, it means having to create a steam account for everyone too.
Sheesh, really badly thought out. I'll keep the game, but can't recommend it for this reason.