Once installed it verifies then you can play offline.
I also hate not getting a copy of the game on disk, this renting a game you bought crap, just sucks and punishes the customer, it will not prevent piracy but it sure makes it inconvenient to install and maintain and now I dont even want to buy a new computer, too much hassle.
Rant off
However D:OS is really a great game, and Steam is better than Blizzards absolutely abyssmal Battlenet.
I would however pay double for an actual disk with the game on it, it makes keeping it around for the future and playing it on more than one computer much more user friendly.
Frakking pirates and frakking companies.
