Hi, I recently finished a project I've been working on using the Raspberry Pi and RetroPie and thought I'd share it here.
The case is 3D-printed and designed to look like the original NES console at 40% scale.
I modelled the cartridge slot to accept little replica carts with embedded NFC tags and rom filenames written to them.
An arduino reads the tags and sends the filenames to the Pi over serial. The Pi then waits for a button press to launch the game.
I had trouble reading NDEF records with libnfc on the Pi itself but found an arduino library that worked for me.
I made a detailed write-up including all the code on my blog here: http://www.daftmike.com/2016/07/NESPi.html
And a quick video going over the features: https://youtu.be/3dgnD93pwX0 more pictures here too: http://imgur.com/a/OkHGP
Big thanks to this community for providing the information I needed to build this project.