First DLC released. You buy 5 loot crates for $9.99 and one of them might unluck the DLC. If not, you just buy 5 more. Crates can also contain nukes to nuke others players, even if this is a single player game. They will die in a violent explosion and get a message that they were killed by you.
Ahh, just kidding. Significant updates has been added since I posted the first time, though, but its free. Time limited offer, just for you. Expires in 12 hours.