Campaign Character Sheets

[ch82]

I think this looks interesting. I wouldn't award xp for killing zombies though but rather completing missions.
Characters who survive get xp/level ups. All missions have the heroes replenish perk except that once a hero dies they are dead in all future scenarios. When zombies win a scenario they do not get XP however they prevent the players from getting xp.
Zombies gain abilities/xp by killing off characters. Equipment/discards/wounds carry over to the next scenario. Also for buildings with pickup abilities. After the first time the pickup is used the chance of finding additional items decreases with each pickup.

(IE you can't go to the gun store run out of ammo and keep picking up the gun you just dropped without eventually exhausting the supply)