In order to run the game properly, the minimum requirements are iOS 11 for Apple devices and OS 5.1 for Android devices (Fire OS 3 for Amazon)
Please note that although your device might meet these minimum requirements, especially Android devices might still be incompatible due to different GPU (graphic processing units), which we cannot test onsite for all devices on the market. 
Additionally, we recommend to have 1.5 GB free space available to run the game smoothly.