Mupen64Plus is regarded as the better performing N64 emulator on Retropie. However the default configuration doesn’t work so well with the XBOX 360 controller.
One of the main problems is that with the default configuration you can only exit the emulator with a keyboard, the emulator supports exiting with a controller however you need to manually configure it. To do that you also need to know your button mappings, i have covered how to find this in this post.
Once you have your button mappings we can start by navigating to the emulator config folder, to do this enter the following:
Then open the mupen64plus.cfg file
sudo nano mupen64plus.cfg
Scroll down the config file until you find “[Core Events]” section, then locate the setting “Joy Mapping Stop”
I use the XBOX Guide button to exit the emulator, this is button 14 however you can use any button, just substitute the button number for the one you want to use.
The value you need is:
Joy Mapping Stop = “J0B14”
J0 is Joystick 0 and B is for button so in this case button 14. Save the file and reboot, you should now be able to exit N64 games and return to the EmulationStation User Interface.