I am not sure that Kotlin competes with Scala in any way. They are trying to remove the pain from Java by providing a concise and safe language (see the quotes from their website below). What are "all the things" they reinvented that were discard in Scala?

> Kotlin is a pragmatic programming language for JVM and Android that combines OO and functional features and is focused on interoperability, safety, clarity and tooling support.

> Being a general-purpose language, Kotlin works everywhere where Java works: server-side applications, mobile applications (Android), desktop applications.