I was doing fine for a long time, until today, I let in about 15 dewellers, placed them in spots that I could, then finished the rest of my work shift. When I came home, ALL the resources were gone! Everyone was sick with radiation and nearly dead, and then to top it all off, I got hit with a Deathclaw attack that wiped out my best people because I didn't have any stimpacks and radaways left. I spent the last hour trying to get resources and everyone back up. I thought this game wasn't supposed to use up resources when it wasn't running...

Did you actually quit the game by exiting to the main menu and then shutting it down?

I don't remember what I did. All I know is I had to start the game all the back up unlike swiping my phone on and continuing.

Essentially, if you leave the game running and the vault **loaded**, game considers you're "active" and resources drain at a constant speed, you must "actively" collect resources to counter that.

If you close the game (warning, the game doesn't autosave when closing the app, but every few... minutes?, so you must manually quit to main menu to "force" a save) or at least leave the game in the main menu (no vault opened), the game will stay in a semi-active status for a few minutes (resources still drain normally, but attacks and hazard cannot happen), and then the vault will shut down (resources will stop draining, only training and wandering remain "active" - actually, the game places a timestamp on the save, and once you return, the game will calculate training time and what happened in the wastes while you where away - ).

Yes you want to swipe to close game or go main menu using the game setting option. I got wiped out this way when I start playing, luckily it was just 20 pop vault so I restarted.

Same here - lost my very first vault that way. Fortunately it wasn't very big so I just wiped that save and restarted.

you have to exit the game to home screen. if you are in a menu screen, resource continues to drop like when you are playing the game yet if you cant harvest the resources; thus only consuming. radiation will rise, health will decline due to food shortage and to top all things radroach or molerats will rise(maybe they also depend on the dwellers resources. should leave some bread crumbs for those ugly bastards). and than there is death claw.

=> make sure you turn off the game. go to main menu whenever you feel the vault is on the track and than make sure you see your home screen.