Ok, so I have a Flex application developed using Apache FB 4.14 SDK. I got it working and approved on App Store and Play Store. Now my client is looking to port the app on Windows Phone. I tried some googling but all I found is about Astoria project, which is recently dropped by Microsoft. So My question from you folks is what is the best way to port the Flex code for Windows phone with minimal efforts?
Sadly, there is currently no easy path from Flex to Windows Phone.
The road map also states no current plans to add support: http://www.adobe.com/devnet/flashplatform/whitepapers/roadmap.html
You will have to port your game to a different engine. How much work that is, and which engine you should use, depends a lot on the nature of your app.
It also depends on if you want to make a Windows code base just for that platform, or if you want to port to something to have one code base for all mobile platforms