RollerCoaster Tycoon 3 for iOS is supported on the following iOS devices with iOS 7, iOS 8, iOS 9 & iOS 10:
iPhones
- iPhone 5S
- iPhone 6
- iPhone 6+
- iPhone 6s
- iPhone 6s+
iPads
- iPad Air
- iPad Air 2
- iPad Pro (9.7" & 12.9")
- iPad Mini 2
- iPad Mini 3
- iPad Mini 4
Unfortunately RCT3 on iOS doesn't run on models not listed as supported, as it requires certain processing features only available on the later model devices.