Awesome, thank you!

Ran the test and determined only the standard 4 buttons are registering. The additional buttons from the 6 button pad do not appear.

I did have this working on previous RetroPies, and also just tested it on my PC and confirmed that all buttons are being registered there. Perhaps I'll reach out to RetroUsb and see if there's a recent compatibility issue.

Appreciate the help.

@respite If you don't like the GUI, then on the same page there's an explanation on how to override the controls for a certain system - MD/Genesis in your case - https://retropie.org.uk/docs/RetroArch-Configuration/#example-per-system-control-override-retroarchcfg. The file you need to edit is the retroarch.cfg in your /opt/retropie/configs/megadrive folder.

@arj5193 once you get into the game press your hotkey & X at the same time.

@retrolover12587
Please do not post a support request without first reading and following the advice in https://retropie.org.uk/forum/topic/3/read-this-first