This is something I've always wanted on the AppleTV. I was lucky enough to get hold of the AppleTV developers kit and here is the result using tvOS beta 2.
The tvOS app is based on Les Bird's code I found here :- http://www.lesbird.com/iMame4All/iMame4All_Xcode.html
The original work is based on iMAME4all which is a iOS universal app, port of MAME 0.37b5 emulator by Nicola Salmoria for all iOS devices (iPad HD, iPhone 4G , iPod touch and older) based on GP2X, WIZ MAME4ALL 2.5 by Franxis.
To get this to work you need
A real Apple TV device, this won't work in the simulator.
Drag the rom zip file into the resource folder in the xcode project so they are copied to the device (Should appear as files in Build Phases/ Copy Bundle resources)
Apple TV - Brief guide to using to play game (Tested with 1942,Donkey Kong, Raiden)
- Turn the controller on it's side (It will work both directions but I found this easier)
- Select rom using up down on dpad
- Press play to select
- Swipe left/right for OK message
- Hold play and press dpad for credit
- Hold play and press dpad for start
- Play game :-)
The code needs some work but you can play basic games
Areas that need work
- Sound - fix arm64 assembler which has been commented out
- Apple TV remote support (WIP)