Fallout Shelter was the first mobile game from Bethesda Game Studios and it won’t be the last. Director Todd Howard tells GameSpot that the studio was blown away by Fallout Shelter’s success and is planning to invest further in that space. “We’re gonna do more,” he told us this week at the 2016 DICE Summit.

Though the Fallout brand is undoubtedly popular, Howard said the team never anticipated Fallout Shelter would enjoy the success that it has.

“I think if you expect, ‘Yeah, it’ll be number one and out-gross Candy Crush for a while,’ you’re generally going to be set up for failure and disappointment,” he said.

Instead of thinking about the money it could make from Fallout Shelter, a point that Howard has stressed before, he said Bethesda’s concern was ensuring it would offer a deep and engaging enough experience.

“Mostly we were concerned with it being appropriate for who we are [as Bethesda Game Studios]–meaning it’s got a bit more meat on the bone than other things like it,” he said. “But its overall popularity? We were not ready for that, which is a good problem.”

Howard also shared some of his favorite mobile games at the moment, listing off titles like Threes, Hearthstone (“I got addicted to that,” Howard says), Clash Royale, Crossy Road, and Star Wars: Galaxy of Heroes.

Bethesda’s drive to make more mobile games comes in part from the simple fact that developers at the studio are already playing smartphone games. As such, they are naturally getting inspired to make their own.

“It’s in your pocket, a lot of [the games are] free or easy to try,” he said. “So every time you’re playing, you’re thinking, ‘We could do one of these, I think we could do something special here.’ So we’re gonna do more.”

Howard did not elaborate any further on what Bethesda’s future mobile games would be. It remains to be seen if they take the form of spinoff games for existing franchises, as is the case for Fallout Shelter, or if they will be entirely new franchises.

In December, Bethesda Game Studios opened an office in Montreal with an aim to “expand its development capabilities in console, PC, and mobile gaming.”

Fallout Shelter was announced during Bethesda’s E3 briefing last summer and released later that evening. It was a quick hit, with players logging 1 billion sessions in the game’s first month on iOS alone. An Android version was released in August 2015.

Bethesda has never said how much revenue the free-to-play game pulled in from its microtransactions, but a research firm revealed that Fallout Shelter made $5.1 million during its first two weeks.

In addition to more mobile games, Bethesda Game Studios is working on Fallout 4’s three expansions, as well as three “longer-term projects.” One of these is “not as big as the other two,” Howard has since clarified.

What would you like to see from Bethesda in the future in the area of mobile games? Let us know in the comments below!