custom scenario help

[chinesewaterbaby]

ok i have a few ideas to get a scenario started but i need help and feed back. the idea was that the bio canisters were what was causing all the zombies so the heros must find them and load them on to the truck on the road out of town. how they find them is by searching the barn, junk yard, or the plant. at least the junkyard (because of the road) and one of the other mentioned pieces must be on the board when created. if all 3 happen to be on the board then you still only need to find 2 bio canisters and the location doesnt matter. how you get the canister is by moving onto the zombie spawning X in the barn, junkyard, or plant and then you may pick up the piece once you stand on the X but it immediately ends your turn. then you must fight the newly spawned zombies then head towards the truck. but its not that easy. every time you start your turn you take a wound from the bio hazardous material. first aid items and events will remove only 1 wound no matter what the card says. you also can not use a ranged weapon wile holding the bio canister but you can set it down at any time after your move action. exchanging the bio canister with another hero in your space is still allowed. if you die from a bio canister wound then you are a zombie hero. the bio canister is dropped on the square where they died and can only be picked up by another hero (maybe if a zombie gets to it will add another spawning pit). once both canisters are loaded on the truck the heros win but if they die or night falls the zombies win. but its not as hard as it may seem. all the heros have a unique advantage corresponding to who they are (limit 2 times)

billy- track star- can roll 2 move dice instead of one
johnny- stiff arm- when a zombie is in the way can push him into another adjacent square and keep moving (at the cost of one from his movement)
jenny- daddy's girl- can use a ranged weapon wile holding the bio canister
sally- small frame-can slip past a zombie in the way- or does not have to fight a zombie in the same square
drifter- lawless- can go through walls (windows) with the canister
sheriff- tough guy- adds an extra fight die
father- believer- always has the faith card**
becky- medical experience- can ignore a bio hazard wound

**faith card- instead of its original effects on the roll of +4 hero does not take a wound

tell me what you think and what i should add, subtract, or change