Super Mario Run is off to a running start with an estimated 3.5 million people downloading the game in the U.S. alone on its first day, according to business intelligence and analyst firm App Annie.

Those downloads in the game’s first 14 hours of availability are surprisingly strong compared to Pokémon Go’s first 24 hours of availability, which saw 4.7 million downloads in the U.S. on Apple devices, an App Annie spokesperson told Polygon.

The question now is, how will Super Mario Run do in the long run?

App Annie analysts think a lot of that will depend on several key factors, like Nintendo’s plans to attract players and to keep them, either through push notifications, daily bonuses or time-sensitive, in-game events.

The company also noted that they believe the free demo is a bit too short and could cut down on the number of people willing to take the $9.99 plunge for the full game.

App Annie said it is also tracking that higher than usual price tag to see what it means both for the game and the mobile game industry.

Super Mario Run takes Nintendo’s popular pipe-leaping, turtle-flipping platform genre and strips it down to the essentials. Mario runs, vaults and even avoids enemies automatically, the player simply has to tap the screen to try and collect coins, do tricks and thwack question boxes.

In our review of the game, we called it an “enjoyable but imperfect adaptation of the Mario games for touchscreen devices,” pointing to the singular control and short playtime as downsides to the game.

That said, the game has obviously found a launch audience on the iPhone.

It took just five hours for the game to claim the top spot for downloads for Overall, Games, Arcade and Action on iTunes, according to App Annie.

“In comparison, it took Supercell app Clash Royale 10 hours to hit the same milestone across Overall, Games, Action and Strategy,” according to a company spokesperson. “As of the time of writing, the game has a four-star rating in the App Store.”

Update: App Annie sent us a bit more data after this story ran. The company estimates that the game had more than 10 million downloads on Dec. 15 worldwide and brought in more than $4 million. They also noted that the game had 20 million pre-registrations (people who clicked on the Notify button in the app store) prior to its release.

Super Mario Run became the top ranked game by downloads in 60 countries shortly after launch, according to the company.