yep, roboVM down. I wonder so what tool can build IOS app use kotlin instead of RoboVM.

http://www.badlogicgames.com/wordpress/?p=3925 and http://www.badlogicgames.com/wordpress/?p=3934

Multi OS Engine is the only production grade option available. Kotlin Native targets iOS however it is in the very early stages of development. Have a look at the Tetris sample: https://github.com/JetBrains/kotlin-native/tree/master/samples/tetris