Bethesda Game Studios, the developer behind the upcoming "Fallout 4," has released a new game for mobile devices based on the "Fallout" series.

Titled "Fallout Shelter," the game is currently available for iOS devices and features game play elements similar to those in "The Sims," Android Authority reported.

Despite being inspired by the "Fallout" franchise, "Fallout Shelter" veers away from the series' general theme. Although the game is still set in a post-apocalyptic world, it does not contain violent and action-packed sequences.

Instead, as a simulation game, it requires players to build and maintain an underground shelter known as a Vault. Their main task is to take care of the Vault's dwellers by supplying their needs. Players can also rescue other survivors roaming in the wasteland and house them inside the vaults. Male and female dwellers can also be paired together to produce babies.

The dwellers can then be assigned to perform various tasks such as gathering resources and scouting the wasteland.

Through the game's rating system and by completing achievements, the dwellers can level up and improve their abilities. They will also gain new weapons and other items needed to maintain the Vault and protect it from attackers.

"Fallout Shelter" was released on June 14 as a free-to-play game. It does not require players to stay online to continue playing the game or pay for various fees in order to speed up its timers.

Currently, the game is only available for Apple's iOS devices. But Bethesda Game Studios confirmed during the recent Electronic Entertainment Expo that it is currently working on an Android version of the game. The studio, however, has not yet announced the possible release date for "Fallout Shelter" for Android devices.

As for the studio's main game and the latest installment in the "Fallout" franchise, "Fallout 4" is scheduled to be released on November 10, 2015, for the Xbox One, PlayStation 4 and Microsoft Windows.