What's it do? Do you need it to play? Seems like a pretty rad game.

The promo code is not required to play the game; I think the only way you can get one is to pre-order the game (I think it comes out in February). The game is, and will always remain, free. I am not sure exactly what it does to the gameplay to have the promo code (I don't think anything really), but I believe when it comes out there will be a server wipe of the characters except for those who have a promo code. THis doesn't really matter anyways for a server wipe since its just an FPS; unlike an RPG it relies more on your skill as a player than equipment and level.

Idk I tried playing it earlier, and these guys were all pissy because he had a promo and was able to do all sorts of shit to own them, whether it was weapons or something.