I can't resist anymore. Sorry. Whomever says you cannot play via lan offline on steam clearly never used steam. I have several games on steam and with the exception of the MP ones, I can play any of them offline. That means, whithout LOGING IN to steam. Now, I wonder how steam.exe would check my account name if I'm not logged in. Magic perhaps? Or are you saying that civ will only be playable as long as you have an internet connection ACTIVE? The only other solution I can see is blocking LAN, as previously mentioned.
On the moral implications of a family using one license to play at different computers, I fail to see the crime. If you think that way I assume that, when you buy a book that more than one member of your family will read, you buy multiple copies? Also, you probably never recorded a tv program for yourself to watch later, because the license paid was for that one-time view, even if you don't share it. When you throw parties, do you pay the required license for the songs you play? I wonder how many people here could avoid that avatar if you start thinking like that...