While the iOS version of the game will become available this December, Android users won’t see Super Mario Run until sometime next year.
On the reason for this prioritizing of iPhones, Shigeru Miyamoto had this to say:
“For us, the stability of the iOS platform was important in choosing iPhones for the game.”
Super Mario Run will release for iOS devices in December 2016. It will release sometime in 2017 for Android.