kotlin-unreal use the Kotlin programming language on UnrealEngine 4


I recently, got some progress on this project and I think its state is worth taking a look by now.

kotlin-unreal allows you to use Kotlin with UnrealEngine 4.

The aim of this project is to provide a good way of writing gameplay code in a productive and maintainable way. I’ve been programming in Kotlin ever since before its 1.0 release, and I cannot talk enough about the productivity boost and code quality this language helps you to deliver. Actually, I am using exclusively this language both at work and on my personal projects, in all kind of different software, including videogames.
So, I thought that bringing this to Unreal Engine 4 was a must for me. Although at the time of writting this, I only made some examples, I already can see the potential of this project, probably as a showcase of what gameplay programming should be on 2021…

You can use virtually every function that is available to a Blueprint by using the Javascript interoperation provided by the Unreal.js plugin.


  • Access to all Blueprint functions and classes
  • A KotlinComponent attachable to an actor to control its behavior
  • Interoperation between variables and functions defined at the Blueprint level
  • Customizable Hot Reload: Apply code updates to everything or to the actors you’re interested in, while in play mode.

From now on, I will be porting an unfinished game I did some time ago to Kotlin, Also, I would be glad to hear what small examples would be interesting for you to see, so I can improve kotlin-unreal. (there are some basic examples already on the github repository)

Github Repository

FPS Example

Hot Reload

Variable Jump Height Implementation with Hot reload

Kotlin homepage: