Civilization – Am I able to play Civilization 5 offline

Playing Civ V in offline mode should allow you to play other steam games simultaneously. I feel compelled to point out, however, that steam only allows one copy of itself to run at any given time, so short of some technical tinkering, you're still limited to one game / steam / computer.

I don't think that there is a physical copy of civ V. Everything I've read indicates that its going to be exclusively digitally distributed.

As far as I know, Steamworks is going to function as the game's DRM which means that even if there's a physical install disc, you'll need steam to play it, even in offline mode.

Civilization 5 is designed to work with Valve's Steam platform.

This will allow you to install the game on any number of computers, but requires you to log-in with steam to play. Since only one steam account can be logged in at once this restricts you to playing the game on only one computer simultaneously.

The exception is that you can run Steam in 'offline mode' to play the game exclusively in single player mode, in which case multiple computers could each play 'offline' at the same time. From what I understand it is not possible to play a LAN game this way, you would need two copies of the game (and two steam accounts). Apparently it IS possible to play on LAN in offline mode. If so, this would allow you to play with your son with a single copy of the game.

This would seem to be a deliberate Steam design choice, for better or worse.

I'm not sure why an ad would specify the number 5, since Steam would not limit the number of installations at all, and only one account could play online at a time.