If you’ve sent Dwellers into the wasteland or queued some crafting before closing the mobile app, you might be wondering, does Fallout Shelter keep running in the background?
This guide answers that question and explains exactly what happens when you’re offline, how time progression works, and what to watch out for when returning to your vault.
Fallout Shelter is available on multiple platforms, but this guide is written with mobile players in mind – whether you’re on Android or iOS.
Does Fallout Shelter Run When You’re Offline?
Yes, but only partially. Fallout Shelter uses a simulated time skip system, meaning that some in-game events will “catch up” when you reopen the app, but the game does not run in real time while you’re not playing.
So while it feels like the game kept going, it’s actually simulating what would have happened based on the time you were away.
What Happens When You’re Away?
Here’s a breakdown of what continues, and what doesn’t when Fallout Shelter is closed:
What Progresses While You’re Away
Resource generation: Food, water, and power will increase based on room output and dwellers assigned. You will need to collect when you return, however. The same applies to Stimpak and RadAway production.
Wasteland exploration: Dwellers continue exploring and will have simulated progress upon return.
Crafting timers: Weapon and outfit production continues.
Dweller training: SPECIAL stat training rooms will continue improving assigned Dwellers up to 1 extra level.
Pregnancy & birth: Pregnant dwellers will give progress after the usual wait time, even while you’re away. You’ll need to claim the baby dweller upon return.
Note: Dwellers in the wasteland can die if they run out of Stimpaks or stay out too long. If you don’t recall them in time, they may not survive the time skip. You will need to pay caps to revive them.
What Doesn’t Progress While You’re Away
Real-time incidents: Attacks (raiders, radroaches, etc.) do not occur when you’re offline.
Dweller deaths in vault: Dwellers don’t die from starvation, thirst, or accidents while you’re gone.
Room micromanagement: You won’t collect resources or trigger rushes until you return.
How Time Is Simulated
When you relaunch Fallout Shelter, the game looks at the real-world time difference since your last session. It then simulates everything that would have happened, up to a point.
For example:
If you leave a Dweller in the wasteland for 10 hours, they’ll have 10 hours’ worth of caps, junk and loot when you return.
If you’re crafting something that takes 6 hours, it’ll be complete when you’re back, as long as that much time has passed.
Note: On some platforms (especially mobile), closing the app from memory too aggressively (e.g. force stopping) can occasionally interfere with time tracking. It’s best to let the game close normally.
Tips for Playing While Offline
Recall explorers before logging off: If they’re low level, have minimal health or are running out of Stimpaks and RadAway. Higher level dwellers may be fine.
Stock Medbays and Science Labs: Return to the game with full healing supplies
Assign Dwellers to productive rooms: Put dwellers in crafting, training and resource rooms before quitting. If you’ve set up your vault efficiently, you should have workers in every room.
Avoid rushing rooms: Do this unless you’re staying online to deal with potential failures
Summary
Fallout Shelter does progress while you’re not playing, but in a smart, controlled way. That means you can take breaks without worrying about total chaos, and return to find your vault in a strong position.
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