Fallout developer Bethesda announced and released Fallout Shelter for iOS during its E3 2015 press conference. The mobile installment in the Fallout series quickly rose to the top of the App Store charts and held the number three spot for revenue for several days.

But Bethesda was uncertain about how Fallout Shelter would do. According to a new interview from GamesIndustry with Bethesda Marketing VP Pete Hines, the studio had to wait on the huge announcement of Fallout 4 before talking about Fallout Shelter. Even then, Bethesda was uncertain about how its new foray into mobile gaming would do.

“If we tried to do this last year without announcing what Bethesda Game Studios was doing [Fallout 4] and said, ‘Oh we’re doing a game and it’s on mobile and it’s called Fallout Shelter,’ we’d probably get lynched, right?” Hines said. “There would be pitchforks at the gate. ‘That’s not the Fallout we asked for, you bastards!’ But doing it this way, they’re like, ‘I’m getting what I want and oh, by the way, while I wait here’s this other free thing that’s fun to play.'”

Bethesda is known for its big console and PC RPGs like Fallout and the Elder Scrolls series. It has not spent much time in the past working in the mobile space, and so Hines described how the studio didn’t really know what to expect from the launch of Fallout Shelter.

Hines stated, “To be honest, I’m not sure what we expected. It’s not like we’re a pretty well-known iOS and iPhone developer where we’ve been down this road before and it’s going to go like this. But it seemed like it ought to be pretty popular, the whole idea of, ‘This thing exists and you can go play it today.’ On the back of all the Fallout 4 stuff, we thought it would do well, but we weren’t sure how well. Suffice to say, we’re pretty pleased right now with how well it’s doing.”

But the studio isn’t content to just allow the game to exist as it is now. Hines went on to reveal that Bethesda has plans for Fallout Shelter, including the possibility of adding new content to the game. He also said that the developer probably won’t begin massive advertising campaigns for Fallout Shelter, although fans should expect some marketing in the future.

“We’re going to at some point do some marketing around it,” he explained. “At this point we’ve essentially done none. And we do have plans for supporting it going forward in the way of content, ideas we have and things we want to try… This is not meant to be a Game of War, Clash of Clans, or Boom Beach competitor. It’s trying to do something different and I don’t know whether or not I see us doing Fallout Shelter TV commercials for it. But that’s something we’ve talked about, and we tend to never rule anything out even if we say, well that’s not something we’re going to do right now.”

Fallout Shelter launched amid a bunch of new reveals about Fallout 4 during Bethesda’s press conference. Fallout 4 will be released on November 10 for PC, Xbox One, and PlayStation 4. Fallout Shelter is currently only available for iOS devices, but Bethesda is planning on putting it on Android devices soon.