why is alto's adventure not free in apple store

On July 8, 2016, the game was released for the Windows platform. The game was released for Android on February 11, 2016. In September that year, Snowman announced that Alto's Adventure would launch on Android and Kindle Fire. The game was released on February 19, 2015, initially for iOS devices. The game was made to emulate the ethereal atmosphere of snowboarding, and was inspired by Ski Safari (2012), Tiny Wings (2012), Jetpack Joyride (2011), Journey (2012), Monument Valley (2014), Tony Hawk's Pro Skater 2 (2000), and Windosill (2009). Snowman, a Toronto-based, three-person indie development team, previously worked on productivity apps before Alto's Adventure. The player taps the screen to jump and perform tricks (backflips), and works towards goals, competitive high scores, and upgrades.

The player-character automatically moves to the right of the screen through procedurally generated landscapes. Alto's Adventure is a 2015 endless runner snowboarding video game developed by Team Alto and published by Snowman (iOS) and Noodlecake Studios (Android).

Why is alto's adventure not free in apple store