On Thursday, Nintendo announced that the Switch had become the fastest selling home video game system of all time in the U.S., selling over 4.8 million units in 10 months. That’s 800,000 more than the Wii did in the same timeframe.

“Whether this is a dedicate gamer who doesn’t want to stop playing Mario or Zelda, or whether it’s a child experiencing these franchises for the very first time, we believe the value proposition as well as the compelling content is what’s fueling our momentum,” Reggie Fils-Aime, president of Nintendo of America, told Fortune.

The Switch is a console that caters both to gamers who prefer playing on their couch and those who prefer their games on the go, but the real secret weapon so far has been the game catalog. Super Mario Odyssey and The Legend of Zelda: Breath of the Wild have been smash hits with critics and fans. Nintendo says 60% of Switch owners now have the new Mario game in their collection, with 55% owning Breath of the Wild.

In the works are new entries in the Metroid and Pokemon franchises and other titles will be announced later this year, says Fils-Aime. Nintendo will also continue to work closely with third-party publishers, who have re-embraced its platform after many walked away from the Wii U, which was a sales flop.

Part of the challenge Nintendo has set for itself with the Switch is a more regular release schedule of big games. Historically, Nintendo has been plagued with delays for major franchises. The game were always big sellers when they did come out, but critics noted the gap between them was long enough to stall sales momentum for the company’s hardware.

Fils-Aime says changes in the development process are helping to resolve that problem, but the company is still laser focused on not releasing a key title until it’s one that has lived up to high internal quality standards.

“We believe we’re doing an excellent job of bringing new young developers into Nintendo,” he says. “We’ve built a large research and development center near our main headquarters in Kyoto that literally houses thousands of developers with new recruits joining all the time. We also have a development center in Tokyo. We’ve got development teams in the U.S. So, for us, part of the answer in speeding up development is having more developers on our teams, learning the Nintendo way of creating great content. In addition, it’s also making sure the quality levels remain high – and that’s why you see long time developers … leading those teams and making sure the content continues to be to our standards.”