Ustwo's optical illusion puzzlerMonument Valley has passed the one million downloads mark.
The game was originally released for iPad last year, but later came to iPhone and Android platforms. A third of all Android downloads for the game are via the Amazon app store, according toTechCrunch.
Players guide a silent princess through levels based on optical illusions, manipulating both the architecture and perspective of levels to create new paths.
Develop has more details.