I started off promisingly, with potential Vault Dwellers lining up outside. I added rooms as quickly as I was able to, to make room for more eager dwellers.
Suddenly, so it seemed, I was running low on all resources. I had to take chances, Rushing rooms to release more resources more quickly. This sometimes panicky behavior resulted in FAILURE.
Failure means the workers will be fighting off Rad Roaches or Fires. Even though I had many of them armored and holding rather nice weapons, they were almost always ineffective and died. In one nightmare scenario which began in the Water Treatment room, I lost half of my dwellers as the roaches swarmed the place.
You can revive dead dwellers if you have the Caps, you can even let them lie there dead with their little tongues hanging out and revive them once you save up the Caps to do so.
The Vault dwellers have S.P.E.C.I.A.L abilities sometimes. They might appear at the Vault door, or be born to a happy couple, or be given in a reward Lunch Box. Because they have no personality, I just try to revive those with particularly good stats. That seems a bit sad, somehow.
Speaking of happy couples, you want to send those with Charisma to the Living Quarters. There, the couple will "court" each other with the all time winners for Worst Pickup Lines.
Soon, they go off behind the partition and smiley faces float through the air. Moments later, they emerge looking as if they're ready to die. Even worse, the woman is pregnant and remains so for a very long bit of in-game time. Life isn't good in the Vault.
My Dwellers are particularly unhappy all of the time. Their mouths are tragically down turned. You are sort of graded daily on your running of the Vault and the happiness of your dwellers. I have had a solid F all along.
I should be discouraged, and after dwellers go down like flies I have bad thoughts of Rushing every room, destroying the Vault, and starting over. Then I peek in to see how things are going, and a few folks have leveled up, and resources are ready to distribute.
We'll try to survive just a bit longer, I think.