Thank you everybody for your help.

I apologise for being so dense, but to refine the question further - when one purchases the full version, is an authentication key provided which can be entered into the game on a computer not connected to the internet?

An appeal to the masses of nuke-crazed fiends: I am horribly addicted to the demo of Defcon , and it is obvious to everyone around me that I must buy the full version. My problem is this: I play the game on my laptop, which is not currently connected to the internet. If I were to purchase the full v...