The Polyglot Developer; Ruby, Python @ iOS, Android, OS X

The Polyglot Developer by Amir Rajan

"...indie game developer that made a minimalist text based RPG called A Dark Room for iOS and Android. The game has ranked at the #1 spot overall on iOS and the #7 spot on Android."

suggestions about Deciding on the Next Language You Want to Learn

• C# => Scala, F#
  
• Ruby/Python => Scala, Clojure
  
• JavaScript => TypeScript, ClojureScript, Elm

Being a Polyglot Programmer with Amir Rajan on the Hanselminutes Technology Podcast: Fresh Air 
for Developers

.NET / Xamarin is not the only mobile portable platform...
I just realized Ruby language could be used for iOS & Andorid Apps with RubyMotion
So can Python, with Kivy

RubyMotion - Wikipedia
"RubyMotion is an implementation of the Ruby programming language
that runs on iOS, OS X and Android. RubyMotion is a commercial product"

Kivy: Cross-platform Python Framework for NUI Development

"Kivy - Open source Python library for rapid development of applications
that make use of innovative user interfaces, such as multi-touch apps.

Kivy runs on Linux, Windows, OS X, Android and iOS. You can run the same code on all supported platforms. It can use natively most inputs, protocols and devices"