People who got the special edition of Dead Island would've noticed the code for some DLC which isn't out yet. Techland have recently confirmed that Bloodbath Arena is releasing towards the end of September, and it will be a horde mode for endless zombie killing fun. For those without the special edition, Bloodbath Arena will cost 800MSP. Worth noting is that those who have the game noticed another DLC package mentioned on the main menu called Ryder White's Campaign. There is currently no information on this package.