Recently I made huge improvements in my project kotlin-unreal.
kotlin-unreal allows you to use Kotlin with UnrealEngine 4.
The aim of this project is to provide a good way of writting gameplay code in a productive and maintainable way.
kotlin-unreal allows you to use virtually every function that is available to a Blueprint by using the Javascript interoperation provided by the Unreal.js plugin.
https://github.com/hiperbou/kotlin-unreal