MemoryTale
Good with a stick
Does it have to be the air that will kill the aliens? Here's a couple more ideas off the top of my head:
There is something out there that will attack the aliens, but not a human. Maybe the aliens are in the food chain to a type of animal. Maybe there are robots out there programmed to attack the aliens. Maybe there are germs that won't hurt humans.
Maybe the aliens see the outside as cursed, or are forbidden by religion to go out there.
Maybe they are worried that once they leave the ship they can't return? Maybe they're paranoid they'll just be abandoned if they set foot (or tentacle) outside?
There is something out there that will attack the aliens, but not a human. Maybe the aliens are in the food chain to a type of animal. Maybe there are robots out there programmed to attack the aliens. Maybe there are germs that won't hurt humans.
Maybe the aliens see the outside as cursed, or are forbidden by religion to go out there.
Maybe they are worried that once they leave the ship they can't return? Maybe they're paranoid they'll just be abandoned if they set foot (or tentacle) outside?
