"Fallout Shelter," the mobile spinoff of the nuclear fallout simulator, is coming to Android on August 13. The free-to-play game is coming to the Google Play store, following its iOS debut on June 14, with some new updates.

One of the new features is Mr Handy, a robotic companion available as a premium reward. Players can send Mr Handy out into the wasteland to collect loot, or scavenge for resources inside the Vault. Mr Handy will also protect you from threats to the Vault, such as Molerat infestations or Deathclaw invasions.

The iOS version of Fallout Shelter was a runaway success, earning $5.1 million in its first two weeks of availability. The developers make money through a "freemium" business model, charging players for extras such as in-game lunchboxes with special items inside.

Fallout Shelter has received praise from all corners of the Web, was nominated IGN Entertainment's "Biggest Surprise" and won Touch Arcade's "Game of the Week." After release, the game was the top downloaded game in 48 countries and top downloaded app overall in 25 countries.

The app's success took developers Bethesda by surprise, who only intended that Fallout Shelter act as a promotional tool for the upcoming "Fallout 4." “The main thing it has done is give us more faith that the gaming audience is enormous, and they don’t care what device they’re playing on,” said Todd Howard, game director at Bethesda.

The new features, including Mr Handy, will be available to iOS players on the same day with an app update.