I haven't tried starting Steam with my internet connection down, but I couldn't get it to start Portal 2 without loading Steam first and it wanted to update Steam before launching Portal 2. But there might be a switch somewhere to let you disable the on-line part of the service and just play.
I played Portal 2 while my cable modem cut out this last weekend. It stays at the "updating Steam" screen for about a minute, fails out to the "Steam can't establish a network connection, do you want to play in offline mode," then you hit "yes I would" and life goes on. There is no special offline mode switch.
Once Steam is updated, though...I'd be curious to see if you can play it without the internet connection.
(Someone else posted after this thread corroborating my suspicion that the internet requirement is on a per-game basis. Steam's need to update, OTOH, would need the internet, but shouldn't be too huge a demand.)
I think the "Updating Steam" is a generic/default state. It isn't actually updating Steam, and there is no update to apply (You can prove that by reconnecting to the Internet later and seeing no update to apply).
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Date: 2011-05-05 05:01 pm (UTC)Maybe it's game variable?
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Date: 2011-05-05 05:06 pm (UTC)no subject
Date: 2011-05-05 05:13 pm (UTC)no subject
Date: 2011-05-05 05:19 pm (UTC)no subject
Date: 2011-05-05 05:33 pm (UTC)(Someone else posted after this thread corroborating my suspicion that the internet requirement is on a per-game basis. Steam's need to update, OTOH, would need the internet, but shouldn't be too huge a demand.)
no subject
Date: 2011-05-05 06:01 pm (UTC)