Leroux: Care to enlighten the ignorant? I didn't know yet that this was false information. I don't want to stir up another Steam discussion, I'm just curious how it works, because when a friend of mine moved and didn't have internet access for a week or more, he wasn't able to start Trine 2 in Offline Mode. He got an error message about Steam failing to connect for an update or something and was offered to play the game in Offline Mode, but every time he clicked on it, the client tried to go online again and gave him the same error message over and over. It didn't seem that easy and fool-proof to activate Offline Mode and put the client to rest, at least not for someone who isn't that familiar with Steam and only wants to play their games, not study how the client works ...
Depends on the wording.
The idea that you have to go/be online *each time* to activate offline mode is a myth that's been going around the internet for a long time. (especially among those not fond of/using Steam). This is partly because of the poorly worded Offline mode FAQ stating it, however they only mean that you have to be online while you set it up properly.
Steam's offline mode can be activated while having no internet at all, it's been like that for years. *However*, it has some serious caveats, and yes that means it's not easy and foolproof, which is something they really need to improve.
It needs to be setup right before using it. Your user/pass needs to be saved on login, and your games have to be downloaded and run *at least once * (finishes install), and have no pending updates before being useable with offline mode.
Beyond that, there's been serious bugs with it. One has been fixed very recently and was probably the worst of them. If you shut down Windows with Steam running it cut off the shutdown process and there was a good chance it'd require to go online next time to fix itself, which meant you couldn't properly put it to offline mode.
Another common one is that offline mode won't activate properly when behind a router or when internet isn't fully gone. Closing the internet connection/router or simply pulling the cable got around that quite easily.
It needs work, and is anything but foolproof, but none of that means Steam's Offline mode requires people to go online for it to work by default. That's only true when something's wrong or it wasn't set up properly yet, which sadly happens too often. In that sense Origin's works much better.