@dpiche Use a vertical theme. I know there is at least one available in the theme list (vertical_arcade, for example). Find one, install it, use it - Theme Documentation

@dankcushions Switching the resolution to Mode 16 (1080p 60fps) in RetroPie seems to have resolved the remaining issue. The game takes up much more of the screen and now looks visibly correct while paired with using "Core Provided" for Aspect Ratio in RetroArch.

Thanks for your help, all! I'm still curious why my display settings got all changed around after upgrading to RetroPie 4.7.20, but I'll leave that to people smarter than me to figure out. :)

Happy classic gaming, everyone! ^_^

@mitu said in Emulation station going off the screen:

Please add some info about your setup, as detailed in https://retropie.org.uk/forum/topic/3/read-this-first.
Are you starting EmulationStation rotated also ?

Yes.

I would add that in the /boot/cmdline.txt parameters, I changed the resolution to 768x768 and everything is now centered and looks correct....except, the top few lines of the [TAB] menu in Mame are cut off....

This is so strange.....