The Retail Game has 2 (two) Modes. They are:-
1 - Multiplayer: Online as per normal, and a Network option, which if you want to use, you must have a dedicated server set up on a PC that will not be able to join the created game (So in other words if your having a LAN, you need an extra machine to run the server)
2 - Play Computer: Allows you to play one or more of the Campains which are comprised of 3 different maps that run one after another, your upgrades are carried over for each map in the Campain, but is lost when a new campain is begun. You can add bots, change their difficulty, and set whether or not they attempt to complete objectives.
So it feels very much like BF 2142, only its about 10 times better. (IMHO)
There is no story driven Campain, I wish there was, It would have been awesome if they could have made it work, perhaps all they would have to have done was knit all the campains together, with story and cutscenes interwoven and then allow you to change your class at a HQ on each map, or just allowed you to carry all the equipment, as you pick it up. Perhaps.
At any rate, its pretty cool, I dont normally like these kinds of games, I wont play any BF games anymore after BF 1942 and Desert Combat, But this is something else, it still feels a bit the same, but the differences it has over the BF games is sufficent to make it stand out from them as a serious upgrade to the genre.
I expect it to become *very* popular, but time will tell.