I've mentioned this before, I will say it again. Steam does not always work in Offline mode and you can be stuck in a cycle where you HAVE to go online to "unbug" it, switch to offline and then you can remove your internet connection and play offline again. I have over 60 games bought through steam, but they are all games I play once or twice through. Nothing I would play for hundreds of hours like any Civ game before it, or a game I want to be able to take with me on business trips. Asking for a simple CD key check / once off online activation is too much to ask for now days it seems.