If you are waiting for FNAF UCN for mobile devices, I have good news for you! You can download the UCN APK for Android from the GameJolt website. Be careful, UCN Mobile is a fan version made by Viktor Nifedow. Scott Cawthon has nothing to do with it. 

Minimum system requirements for UCN Mobile.
Android 4.2+ (may have syntax/parsing error on 7.0+)
CPU: ARM/x86 Dual-core 1.0 GHz
RAM: 1 GB for the game. (You should have more than 1 GB. For example 1.2+GB)
GPU: Mobile graphics with OpenGL ES 3.0 support.
Screen: game's native resolution is 1920x1080.

Unfortunately, the mobile version of UCN is not available for iOS. 

If you played UCN on your Android device, share your experiences.