I’m assuming you downloaded a new image? If so, maybe the dev has put it in the image. That’s really the only explanation that makes sense. :) You can probably run it just by selecting it and pressing A/whatever you’ve mapped to your select button? I’m not sure though. Good luck!
Re. Changing screen resolution: I’m not entirely sure on how runcommand.sh works through es_systems.cfg, but looking through the code it looks like it uses tvservice. I decided I’d go ahead and test some through the command line, but I can’t find a tvservice mode that works. I tried basically every item under the CEA and DMT return of tvservice (tvservice -m “CEA/DMT”) but each either makes minecraft too big for the screen or too small. Is there a way to explicitly state resolution, without having to go through set modes?