Screenshot by Michelle Starr/CNET

If you want to take the post-apocalyptic Wasteland of Fallout with you wherever you may go, this is your chance: In a surprise announcement in its E3 keynote, developer Bethesda has revealed Fallout Shelter, the developer's first Fallout game for mobile.

According to VP Pete Hines, the Bethesda team had been talking about making a Fallout game for mobile since 2007 -- when Fallout 3 was in development and when the iPhone was released for the first time.

"We kept talking about this one that would be perfect on a touchscreen, and it would be no better anywhere else, so we decided to do it."

In Fallout Shelter, you are the overseer of your own Vault. It's essentially a town management sim in which you must keep all the residents of your fallout shelter happy and healthy.

"This is inspired by other games we love, going back 30 years to Little Computer People. You'll see inspirations obviously from XCOM, Sim City, FTL, things that we really really like," Hines explained.

Screenshot by Michelle Starr/CNET

Each resident has stats and can be levelled up, and can be equipped with outfits, weapons and gear that they'll need when you send them out into the dangerous Wasteland in gameplay inspired by an RPG called Progress Quest.

You'll also need to collect and manage resources, maintaining the right balance of food, water and power to keep your residents alive. You can also assign your residents jobs and train their stats. Rewards are offered in the form of lunch boxes, which contain a selection of loot.

Random events will include disasters within the vault, such as fires and attacks by Wasteland raiders, and you can even get new residents when your current residents have babies.

The game is free to download and play, too.

Screenshot by Michelle Starr/CNET

"Don't worry, there are no paywall timers, you don't need an internet connection. You build something, it's instantly built. Again, no internet connection, you can play anywhere," Hines said.

"We do let you buy more lunch boxes if you want more random loot, but the whole goal of this game was to do something we'd really want to play on our phones, something that would make us smile and with more depth than what we were seeing."

This is not the developer's first foray into mobile; in 2012, Bethesda Softworks released a game for iOS called Dishonored: Rat Assassin, a sort of Fruit Ninja with rats. It is no longer available on the iTunes app store.

In addition, Bethesda announced The Elder Scrolls Legends, a competitive card game that will be available on PC and iPad coming at some point later this year.

Fallout Shelter, however, is available right now from the iTunes app store. (The Android edition is in the works and should be out in a few months.)

Follow all the latest news from E3 2015 on CNET and GameSpot.