Ron, you can play Steam games w/o an Internet connection, but you need the 'net initially in order to register the game. After doing so, you can disconnect from the Internet, run Steam, Steam will note that you're offline (as long as you have the settings checked properly to cache your user information on your PC), and let you play anyway.
It took Valve a long time to get this working right, but now it does. It was a mess for years.
-HM
Last week I was out of country on work and took my laptop. Could I get Left 4 Dead 2 to work without an internet connection? Could I bollocks. It took Steam about 3-5 minutes of being locked and useless after starting till it told me it couldn't find an internet connection and then I select Offline mode.
When I tried to start L4D2 in Offline Mode it would try and update Steam and just sit there. When I used a hotspot Steam didn't need updating. I ended up playing Blood Bowl single player and a bit of Demigod.