Mike Frazzini, a longtime Amazon.com Inc. employee who helped start Amazon Game Studios, is stepping down. The executive told staff he was leaving to focus on his family, said Amazon spokesman Ryan Jones.

“Mike was there at the beginning of Amazon Games, and his leadership and perseverance helped build the games business from the ground up,” Jones said in a statement.

“Our recent successes with New World and Lost Ark are the result of the long-term, customer-focused vision for games he helped establish. We are very grateful for all his contributions, and wish Mike the very best,” Bloomberg quoted Jones as saying in a report.

Amazon Game Studios was an expensive endeavor for the e-commerce giant, costing hundreds of millions of dollars a year, but for years failed to produce hit games, according to the Bloomberg report.

Frazzini, who previously worked in the books section of Amazon, was a relative game novice when he became head of the division. Some employees had criticized him for veering too far from game-making’s traditional playbook, Bloomberg reported last year.

After cancelling, and even once unreleasing, games at various stages of development, the company did have a breakout hit this fall with its release of online PC game New World.

At a conference soon after the game’s launch, Amazon Chief Executive Officer Andy Jassy said that gaming could become the company’s largest entertainment category.

Following New World’s warm reception, former Amazon boss Jeff Bezos tweeted: “After many failures and setbacks in gaming we have a success. … Don’t give up no matter how hard it gets.”

But even New World’s success faded after its initial release. The game had 913,000 concurrent players by late September, and now has about 26,500, according to data from Steamcharts. One former Amazon Game Studios manager, who asked to remain anonymous because they weren’t authorized to speak publicly, said that Frazzini’s leadership of the unit suffered because he had not had prior experience in gaming.