Some secret in Fallout Shelter

As far as I can tell, starvation and thirst don’t kill you. They lower your health to about 20% and radiation to 50%. This, of course, leaves you highly vulnerable to raiders and radroaches.

Dwellers in the wasteland don’t starve or irradiate. They put a drain on your resources, but don’t actually suffer if you’re out of them. This includes dwellers who have returned to the vault and are waiting to get back in.

Children, pregnant women, and dwellers in the wasteland are all immune to damage from radroaches, raiders, and fires.

Low happiness doesn’t affect the probability of success on a Rush.

Theres nothing in the vault but a power room, residence, science lab, and medbay. All of these are staffed by pregnant women. There are as many men as there are pregnant women standing outside the vault waiting to come back in. When a pregnancy ends, a man comes in and immediately starts a new one. All of the rest of the dwellers spend all their time exploring the wastes. They occasionally come back to briefly partake of the stimpaks and radaways produced by the vault. Low happiness mostly prevents production, but because everyone in the vault is immortal I can rush with impunity. When children grow up, they are sent out into the waste before they can be killed by radroaches.