For example: Can I create a project from Tappy Chicken, build ipa and sell it on AppStore ?
Yep! If you want to sell Tappy Chicken 2: The Sequel, you are completely welcome to do so.
Welp! There goes my plan for the next big game. Thanks Jonathon. 
You could even take assets from those projects currently on the Marketplace, transfer them into your project that you are currently working on, and then release it on the AppStore. Here is a link on how to release your game when it is complete: Release and Royalty Tracking Guidelines - Unreal Engine.
Hope this helps to solve your issue. Have a great day!