Given the huge difference in scale between the two games, that Fallout Shelter made around a third of that is impressive.

Bethesda’s success in the space is certainly promising when we see a free-to-play landscape that is packed with divisive titles. There was a different kind of player joining the game. It implies a multiple-storied bunker, called “the Vault”, in which players need to keep their people safe from nuclear bombs.

While Fallout Shelter is free and as Bethesda claim no money needs to be put into it at all, the incentive is there still to put real-life money into the purchase of lunchboxes. For building rooms or getting items, users need to send out some bunker dwellers in order to gather resources that will pay for lunchboxes. With that in mind, ardent followers of the extremely popular post-apocalyptic RPG series have had to little else to do other than while away the hours in veritable vaults of their own, as they wait for the game to come out.

Fallout Shelter is only available on iOS now. Bethesda Studios refused to report how much the app cost to develop, but there was no doubt in its success when it was admittedly “infinitely profitable”.

SuperData, a provider of market information on digital gaming, reports that Bethesda has made over $5 million on Fallout Shelter.

This is telling of the free-to-play model, but it also shows a lot about the popularity of mobile gaming too, with the ability to not only target the gamers looking forward to Fallout 4, but also tap into the powerful casual gamer market the money is there if the game is designed right.

Even though the game is only available on iOS platform, Fallout Shelter managed to overpass Candy Crush Saga from top 3 highest grossing mobile games for iOS.