But I agree with the previous poster that a 4e Midnight would work best where the heroes are actually badass heroes. They are just all alone against an overwhelming and pervasive darkness. 4e wouldn't work as well in a game where the DM wants their players struggling to figure out where their next meal is going to come from. Personally, I don't think 3e does that kind of campaign very well either. For that kind of survivalist game of Midnight, I'd recommend tracking down a copy of Green Ronin's 2nd Edition Warhammer Fantasy Role-play and use that instead.
Before I read the 4E Dark Sun setting I would have agreed, but Dark Sun is good enough to make a believer of me. The inherent bonus system is an obvious include, with magical items being rare and potentially dangerous (and the magic item 'powers' being replicated by boons and other systems, per DMG2/Dark Sun).
Dark Sun is another Crapsack World where most good and hope have fled the land, people struggle to survive, and any heroism the characters engage in seems downright unnatural at times - giving them a stark choice between giving in to the darkness/despair/evil surrounding them or attempting to stand as the light of hope in a world that eats such naive and ridiculous ideas.
Actually the Dark Sun book wouldn't be a bad pickup in general for trying to run this. Obviously a lot of the desert stuff doesn't necessarily apply, but the tone does.