Can you, with a straight face, and with honesty, claim that any closed source, proprietary game is under your control? Can you answer this last question without "but"s?
For most games, you have to agree to a EULA. This restricts what you can and can't do with that game.
I think you're own criteria will restrict your game playing experience to FOSS games.
And your question implies you HAVE to be online to play CiV, which is not the case. Steam isn't like Ubisoft's new DRM scheme. You can play steam games in offline mode.
On the other hand, you can store your saved games on the Steam cloud, download the game any number of times on any number of computers, don't have to worry about physical media being scratched, don't have to worry about downloading latest patch, and a bunch of other things.
The only thing about CiV that I am not liking is their move to monetized DLC micro-transactions. Preorder "Digital Deluxe" and get and an exclusive civilization??? ARGH!