This year’s Electronic Entertainment Expo had more of a focus on powerhouse sequels and virtual reality, but mobile certainly had its place as well, especially with EA and its showcase, featuring the likes of Minions Paradise, among other games.

But one bombshell that truly dropped this week was Bethesda’s Fallout Shelter, a game that arrived on the App Store as a tie-in with the forthcoming sequel Fallout 4. The game was revealed during the company’s press conference this past Sunday, and made available within just hours after it concluded. The demand for it has been great, but even Bethesda couldn’t have foreseen just how successful the mobile spin-off would become.