Language Tutorials
C#
Tutorials Point – Good overall C# tutorial
Cross Platform Games Development
Marmalade – C++ based framework with easy deployment to all platforms. Free basic version with paid plans.
Haxe – Language that compiles to many different platform targets, including JavaScript, iOS, Android, PHP, C++. Opensource, totally free.
Cross Platform App Development
Xamarin – C# based cross platform
Cordova – Apache foundation project for HTML5 xdev
- Intel in-app purchases for Cordova
PhoneGap – Based on Cordova