So I downloaded the Breakdown DLC a few days ago but only got around to trying it out today. It basically gives the game a sandbox mode with an ever increasing difficulty and reliance on supplies. Played it for a few hours today, fuck is it harder than the regular game. I died like 4 times already. I unlocked my first "hero" today, and started using him after my main character died. He also died a few missions into area one. Then I start a new game, and he spawns in a different spot. I literally run maybe 30 meters and I am attacked by a feral zombie. The DLC mode seems to have you take a ton more damage and get sick/hurt status a lot easier so you have health/stamina penalties easier. I got pegged a couple times when I spawned so I was already hurt when I ran into the feral zombie, he literally grabbed me and due to my low health, just ripped me in half. Like 2 minutes into the game, it was over and I had to respawn. Awesome. I think the DLC just made this my game of the year.
Anyways, 360/PC people, check out the DLC if you haven't already.