Fallout Shelter may have made $5.1 million in June, with an Android release still to come on 13 August, but Bethesda's Pete Hines has stated that the success will not change the company's approach to mobile development.
"This isn't the start of a formula where every time we make a game we need to do a mobile game," he told IGN.
"That's not why Fallout Shelter was great."
"People appreciate the game because it doesn't have our hand in your pocket. It did monetization in a way that people didn't have a problem with," he went on.
"If we just start saying yes [to more mobile games], we start getting into this thing where eight games will fail and two will succeed."
However, it's worth remembering that Bethesda also has The Elder Scrolls: Legends on the way, a free-to-play card battler based on the popular RPG series.
If that one also makes it big, then it'll be interesting to see if Bethesda becomes inspired to rethink its mobile strategy.