Kotlin is cool but it's not C#. The project that's most "C# for the JVM" is called Stab and it's widely rumored that it was (as its an anonymous project) a precursor to Kotlin on the side.

RemObjects C# is exactly that. C# language, compiles for JVM (and Cocoa and .NET and native Windows/Linux/Android NDK, as well).

Projects by no-name companies too insecure to open-source their stack but also too shameless not to flog it every chance they get are not worth even considering. Programming languages that aren't fully and permissively open aren't worth a bucket of spit. And I don't provide my business to the latter, either.

Especially when superior options exist, because "C# on the JVM" also isn't even particularly valuable when you're a competent programmer who is capable of learning new things.

Not really.

Kotlin does not support value types, unsafe low level coding, and it is going to be a while until it can match .NET Native.