I developed Hexagon heavily inspired in these great tools because of the following reasons:

• Take full advantage of the Kotlin programming language without any strings attached to Java (as a language).
• I wanted to be able to replace the HTTP server library used with different adapters (Jetty, Netty, etc.) and though right now there is only one, more are coming.
• Have a complete tool to do full applications, though you can use other libraries, Hexagon comes with a dependency injection helper, settings loading from different sources and HTTP Client, so it comes with (batteries included).

Right now I'm using it for my pet projects, and I'm happy with it.