Chances are, you're already expecting some kind of exclusive DLC/boondoggle from Activision's big releases. Prototype 2's not going to disappoint you, then.
Radical Entertainment's open-world action game will be getting something called a RadNet Edition. The twist here is that the RadNet Edition won't cost you anything extra. (However, you will need an internet-connected platform to take advantage of the RadNet program.) This fancy version will come with a one-time use code that allows for access to special challenges, unique mutations and competitive score events tracked on leaderboards, as well as avatar items and dynamic themes. Only the first wave of Prototype 2 will be RadNet Edition copies, meaning that you can only get the content by buying it new. If you participate in all the challenges, you'll unlock a super-special shape-shifting mutation that Activision's keeping under wraps. My guess is that it'll be the ability to play through Proto2 as Alex Mercer.
Activision's claiming that the RadNet content will only be available for seven weeks after Prototype 2 comes out so, if you want the perks, you need to get the game as soon as it comes out and check in every week. It's not quite as pernicious as Call of Duty Elite pay-to-get-stuff-first since there's no added cost and RadNet essentially amounts to a loyalty program.