MetroidArch is a fork of RetroArch built for one thing: playing Super Metroid on a dual screen Android handheld (built and tested on the AYN Thor) with real widescreen rendering on the main screen and a live second screen showing your HP, ammo, map and item collection while you play.
This is not a general purpose RetroArch build. I stripped this down to focus entirely on Super Metroid, so don't expect the usual "run any system" experience here. It installs alongside a normal, unmodified RetroArch install (different package name, different app name) so you don't lose your existing setup.
- Open the app, go into Online Updater, and run Update Assets and Update Core Info Files. Without this the app won't work correctly.
- Close the app completely and reopen it.
- When picking a core, choose one of these two:
- Nintendo - SNES / SFC (bsnes-hd beta), for real widescreen
- Nintendo - SNES / SFC (Snes9x), if you don't want widescreen
You might see other cores or entries in the list too, ignore all of that, only use one of the two above. See What you need below for more on the difference between them.
| Main screen, widescreen | Second screen, not in gameplay |
|---|---|
 |
 |
The main screen renders in real widescreen (bsnes-hd beta only, see below). The second screen only shows the live map/HP view while you're actually playing, it drops back to the logo the moment you're in a menu, paused, or watching a cutscene.
| Second screen, room map | Second screen, world map |
|---|---|
 |
 |
The room map (left) tracks your current room live and tints to match whatever area you're in, with the HP/ammo strip along the top, tap an icon there to arm it. The world map (right) shows every area you've explored so far, with real area labels and door connectors between them.
| Second screen, items tab | Second screen, setup tab |
|---|---|
 |
 |
The items tab shows your full equipment list, item collection percentage, play time, and a suit wireframe that changes with whatever you actually have equipped. The setup tab has a status bar toggle for each of the three tabs, Hide Main HUD, and Clear Map Markers.
This build only works properly with two specific, patched cores:
- bsnes-hd beta core - if you want real widescreen. This is the heavier option and needs more system resources, so it won't run at full speed on slower devices.
- snes9x core - if you don't care about widescreen and just want the second screen features on a normal 4:3 picture. Lighter on resources.
Both cores had to be patched by hand to expose the memory access and HUD control this app needs. I bundled both patched cores directly into the APK, so a normal install already has what it needs, you don't have to go find and build them yourself. If you ever run RetroArch's own Online Updater afterward, it might overwrite one of these cores with the stock version, but the app checks for that and quietly repairs itself the next time you open it.
If you want to look at what was actually changed in each core, here they are:
- bsnes-hd fork: https://github.com/Raekwon1603/bsnes-hd (branch
metroidarch-wram-access) - snes9x fork: https://github.com/Raekwon1603/snes9x (branch
metroidarch-wram-access)
Both are real forks of the original projects, upstream credit below.
If you want widescreen, you need to select the bsnes-hd beta core specifically. Here's the setup for the widescreen patch itself, it's easy to get wrong if you haven't done it before:
You need a Japan/USA ROM of Super Metroid, and you don't patch the ROM itself, you add two extra files next to it instead.
You need a specific version of Super Metroid: "Super Metroid (JU) [!] (UH).smc", with a CRC32 of D63ED5F8. If you're not sure your ROM is the right one, check its CRC32 with an online tool and compare. If it doesn't match, you'll need to track down the correct version elsewhere, I can't provide ROMs.
Then grab the patch files from here: https://forum.metroidconstruction.com/index.php/topic,5168.msg70656.html#msg70656
Download the BPS and BSO files. Once you have your ROM plus both patch files, all three need the same base filename, just different extensions. For example:
Super Metroid Wide.smc
Super Metroid Wide.bps
Super Metroid Wide.bso
Put all three in your SNES ROM folder and load the game with the bsnes-hd beta core selected. That's what actually turns on the widescreen rendering, the patch files alone don't do it.
Load the ROM as a plain, uncompressed .smc/.sfc file, not zipped. RetroArch can normally load
ROMs straight out of a zip without extracting them, but the second screen reads your ROM file
directly to decode the map and item art, and that part can't reach inside a zip. If your ROM is
zipped, the map will get stuck on "Loading Map..." forever and the items tab won't show real data
either. Extract it first and point RetroArch at the actual .smc/.sfc file instead.
Worth knowing before you go in: the widescreen rendering can have some visual glitches here and there, mainly during big boss fights and cutscenes. It's not something I patched around, it comes from the widescreen patch itself pushing bsnes-hd's HD mode past what it was really built for in those specific scenes. Normal exploration and regular gameplay are fine.
If you'd rather skip all of this, just use the snes9x core with a normal Super Metroid ROM. You get the whole second screen experience, just without widescreen, and it doesn't need any of the extra patch files above.
MSU-1 works alongside the widescreen patch too, confirmed by someone in the community. Just rename the widescreen patch files to match your MSU-1 pack's filenames and drop them in the same folder, same idea as the setup above. You might get a freeze on the "Last Metroid" dialogue on the very first boot, if that happens just back out and load it again, it works fine after that.
I've also tried this against Super Metroid Redux (GitHub) by ShadowOne333, and everything I tested worked correctly. Redux has its own dedicated widescreen patch (also by ocesse), built specifically for the Redux v1.5 ROM, so don't use the vanilla widescreen patch above with it, get the Redux one instead in the romhacking.net download link and set it up the same way (matching filenames for the .smc/.bps/.bso, same as above).
The map, HP strip, items tab, Hide Main HUD, map markers and the per tab status bar toggles all worked normally in what I played. The one thing that doesn't work is tapping an ammo icon on the second screen to arm it, Redux rebinds ammo switching to its own shoulder button controls internally, so it doesn't go through the same memory address vanilla Super Metroid uses for that. Not a big deal since you can just use the shoulder buttons like Redux intends.
I haven't played far enough into Redux to call this fully verified though, I don't plan on adding proper dedicated Redux support since my main focus is vanilla Super Metroid, but if anyone wants to play more of it and try the second screen features throughout, I'd be curious to hear how it holds up. Open an issue if you run into anything.
The second screen shows the METROID logo while you're in a menu, cutscene or paused, and switches to the live view the moment you're actually playing.
Map tab - your current room, zoomed and pannable, tinted to match the area you're in (Crateria, Brinstar, Norfair, Wrecked Ship, Maridia, Tourian each get their own color). Tap the button to switch to the full world map, showing every area you've explored so far with real area labels and the doors connecting them. Pinch to zoom or use the on-screen buttons, drag to pan. Long-press anywhere on the map to drop a marker (long-press it again to remove it), useful for "come back here later" spots. Markers are saved per save file, so they won't follow you if you switch to a different save slot or a different ROM.
Items tab - your full equipment list (suits, beams, boots, misc. items), your item collection percentage, play time, and a full color wireframe of Samus that actually changes depending on which suit you have equipped.
Setup tab - a status bar toggle for each of the three tabs (so you can show it on Map but hide it on Items if you want more room, for example), a Hide Main HUD toggle that blanks out the HUD on the main screen itself, and a Clear Map Markers option (needs a second tap to confirm, so you don't wipe your markers by accident).
The HP/ammo strip at the top shows your energy, missiles, super missiles and power bombs live, and you can tap directly on an ammo icon to arm or disarm it, same as pressing select in game. This works from any tab now, not just the map.
I didn't touch save states or autosave-on-exit here on purpose. RetroArch already disables save states under RetroAchievements hardcore mode, and turning that back on (or off) is your own call to make in RetroArch's own menu, not something this app should override.
Everything described above is either read-only (map, HP, items) or purely cosmetic (Hide Main HUD blanks the screen through the same DMA path the game itself would otherwise use to fill it, it never touches any memory RetroAchievements cares about). None of it should conflict with hardcore mode.
None of RetroArch's own RetroAchievements code was touched in this fork either. The cheevos/
folder and the deps/rcheevos/ library it's built on are exactly the same as upstream, untouched.
I know "trust me" isn't worth much on its own, so rather than just claim it, here's the actual
full diff of everything I changed in each repo, compared straight against the real upstream
project. You can go through it yourself and see there's nothing in there touching achievements,
save states, or anything else that would raise a red flag. If you spot something I got wrong or
missed, please open an issue, I'd genuinely rather know.
- MetroidArch vs upstream RetroArch: https://github.com/libretro/RetroArch/compare/master...Raekwon1603:RetroArch:metroidarch-dual-screen
- bsnes-hd fork vs upstream bsnes-hd: https://github.com/DerKoun/bsnes-hd/compare/master...Raekwon1603:bsnes-hd:metroidarch-wram-access
- snes9x fork vs upstream snes9x: https://github.com/snes9xgit/snes9x/compare/master...Raekwon1603:snes9x:metroidarch-wram-access
I'm honestly not that experienced with emulator internals or the RetroArch/core source code, so I used Claude (Anthropic's AI) while building this, especially for figuring out where in these massive codebases I actually needed to make changes, and for a lot of the real detective work on the bsnes-hd and snes9x patches. I wanted to be upfront about that rather than pretend I did all of this alone.
This wouldn't exist without a lot of other people's work:
- RetroArch and the wider libretro project, this whole app is a fork of it.
- bsnes-hd for the widescreen/HD core this build depends on.
- snes9x for the lighter, non-widescreen core option.
- ocesse, for the Super Metroid widescreen patch (both the vanilla and Redux versions), from the Metroid Construction forums.
- ShadowOne333, for Super Metroid Redux (GitHub), which this build also supports (see above).
- My own separate project, super_metroid-android, a from-scratch native Super Metroid engine port I built earlier - the whole second screen design (map, HP strip, items tab, markers, settings) is based directly on what I already built there, just ported over to work as a RetroArch companion screen instead.
Since this is a fork, the original RetroArch project info, its own docs, support links and so on still apply to the underlying frontend this is built on. You can find all of that on the real RetroArch repository.