Another route would be to match a Picade with a Picade Console which would give a second set of controls but with a shared screen. Just connect the Console to the Pi in the main unit, reprogram the key mappings and away you go! :-)
I have been thinking about going the second route since building my picade a few weeks ago. I did not even know the first route was possible, do all the emulators support network play for multiplayer or is it just the arcade emulators that work that way?
I’ve been reviewing this as an option also. I’ve tried netplay between my picade (RP4) and tested it by connecting it via ethernet to my other stand alone RP4.
2d gaming works fine, but the psx has a lot of freeze frames. Looking to see if there’s something to improve especially for the psx