[1][2] They rescue dwellers from the wasteland and assign them to different resource-generating buildings in the Vault, using the SPECIAL statistics system from the other Fallout games.

Each character's SPECIAL profile affects their ability to generate different resources,[3] and their statistics can be increased by training them in rooms devoted to each stat.

Players are not required to spend money in order to accelerate long timers or processes,[2][5] instead having the option to rush the room at the risk of triggering an incident – such as fires or "radroach" infestations.

[9] On November 5, 2009 John Carmack, who at that time worked for id Software, said that while it was nothing official yet, he had an internal proof of concept made for a Fallout iPhone game.

"[10] Fallout Shelter was announced by Bethesda during its press conference at the Electronic Entertainment Expo on June 14, 2015, where it was confirmed the game is a free-to-play title that would be released for iOS the same day.

Preston Garvey, the leader of Commonwealth Minutemen, was added as a reward available from lunchboxes, along with his Laser Musket weapon, which can be equipped by other Vault dwellers.

[16][17] On July 10, 2015, the game received its first update which fixed some problems while adding a new "Photo Mode" feature that allows players to capture and share images of their Vault.

[19][20] On October 15, the game received update 1.2 that added cloud saving, survival mode, Russian language support and Piper, a character from Fallout 4 available only for iOS version through lunchboxes.

The update added a statistics page, ability to skip tutorial and a new gameplay feature where dwellers can loot equipment from dead raiders.

[29] Update 1.5 was released in April 2016, adding customization options for Vault dwellers along with the ability to scrap unwanted items and support for 3D Touch.

[30] Update 1.6 was released on July 14, 2016, adding a quest system, two new enemies (Feral Ghouls and Radscorpions) and two items in the shop.

[31] Update 1.6, along with the PC version of the game, was announced at Bethesda's press conference before Electronic Entertainment Expo 2016 held on June 12, 2016.

[39] In a suit filed in a Maryland U.S. District Court, Bethesda alleges that Westworld — developed by Behaviour — "has the same or highly similar game design, art style, animations, features and other gameplay elements" as Fallout Shelter and Westworld illegally "uses the same copyrighted computer code" as Fallout Shelter.

[40] Bethesda sued for copyright infringement, breach of contract and misappropriating trade secrets, seeking a jury trial and damages.

"[47] Justin Davis of IGN remarked "Fallout Shelter is desperately in need of a set of endgame goals or resource sinks to look forward to.

Jeb Haught of Game Revolution opined, "when I add the micro-transaction advantage to the post apocalyptic mix, the result puts a sour taste in my mouth".