I've recently pined for playing some games on the go on a device less clunky than a Steam Deck - re-visiting or finishing things that I never finished. Maybe I'm getting old..

Anyways, I saw that Anbernic released a cute new little SP clone - a clamshell emulator running with retroarch, supporting ROMS up to PSX, essentially. It was reasonably priced (link at bottom), so I decided to grab one.

I've got to say, it is nice to have a clamshell device like this. I can close up and toss in by backpack as I travel:

Using the device, one of the things that I immediately felt could be improved was the firmware it comes pre-loaded with. It ships with a stock Anbernic firmware and a bunch of goodies. I found the firmware a bit clunky - lacking swiftness, and wanted a more simple and sleek interface.

I decided to give MuOS a try: https://muos.dev

⚠️ Please note that as of writing this, the following functions on the XX-SP do not work with muOS:

• Bluetooth

The following will serve as a guide to installing and tweaking things for MuOS on the RG35XX-SP. It assumes that you are using a PC/laptop running a linux distro (trying to use coreutils as much as possible).

I will add things to this README as I make changes that seem.. interesting enough to document here.

Latest version of the firmware can be downloaded from https://muos.dev/release/plush.

Let's just do this in terminal:

wget https://dl.muos.dev/RG35XX-SPLUSH24/muOS-RG35XX-2405.1-REFRIED.zip

unzip RG35XX-PLUSH24/muOS-RG35XX-2405.1-REFRIED.zip

Cool, its downloaded and extracted now.

Dust off a decent MicroSD card from your bin of tangled cables or wherever you keep them. I recommend a 64GB size.

Plug it into your linux machine.

⚠️Make sure you are pointing this to the right drive, so that you don't obliterate important data! df -h, gnome-disks, or gparted might help you better visualize this better before imaging.

When you are ready, go ahead and start imaging with the following one-liner:

sudo dd if=muOS-RG35XX-2405.1-REFRIED.img of=/dev/sdc status=progress && sync

*/dev/sdc should be replaced with your proper drive for the card

Once this is finished, we can eject the card from the machine and load it back into the TF1/INT1 slot at the bottom of the XX-SP.

Hold the power button down until you see the green light on the side appears (takes a few seconds).

The splash screen with the muOS logo will appear.

Within the "DEVICE TYPE" section you first see, make sure to select "RG35XX-SP".

After this, Let the device do its thing, setting up the system - you will see a lot of Factory Reset messages, but don't worry, it will keep you up to date with the process (even providing you with silly quotes along the way).

After 5-10 minutes this process should complete and you will be brought to a dashboard. Go ahead and hold the power button for a few seconds to turn the device off and take the MicroSD card out of the XX-SP and back into your linux machine.

Before changing anything else, consider this as a 'back-pocket': These are all the stock shortkeys for muOS, which I find super helpful to memorize:

It might even be a good idea to just clone this repo and save these somewhere, or save the following image to your XX-SP to view in case you need it (maybe not worth it):

muOS seems to install some popular/less-legally-concerning BIOS files for emulating gaming systems. For any other BIOS files you want, you'll have to fin them on the internet and simply add them to the following path on the MicroSD:

../MUOS/bios

⚠️ The firmware uses an exfat type partition to retain the files - so depending on thedistro you are running with you might need to download the exfat-utils package with your package manager.

Your MicroSD should auto-mount on most systems, and when you open up the removable media in the file viewer you have installed, you should see this folder:

../ROMS/: top-level folder where the ROMS and BIOS live.

All subfolders of that directory can be created based on the system, so things like:

• ../ROMS/SNES/
• ../ROMS/NES/
• ../ROMS/GAMEGEAR/

You can place your roms in the appropriate folders from there, and muOS will do a good job of picking them up and finding the appropriate emulator to run them with. If you ever run into issues with thise, check the configurations in RetroArch using the proper shorkey mentioned earlier.

You can easily install and switch themes for the muOS system.

These are bundled and compressed in .zip files. When you download these you usually have to do one of two things:

• Sometimes you can just move the .zips into the ../muos/THEMES/ directory of the MicroSD card you have muOS installed on, no need to extract anything yourself from your linux machine. When you turn the XX-SP on you should just see these in the Themes section of the Config menu.
• Other times you will need to move them into the ../ROMS/ARCHIVE/ directory of the MicroSD, still no need to extract from your linux machine. Then from the XX-SP you can install these by going to Apps > Archive Manager > {select the .zip you want} > A BUTTON

Usually on the site hosting the theme the creator will speifcify where these need to go, anyways.

And to change the theme from your XX-SP: Config > Theme Picker > {select the theme} > A BUTTON

There are lots of crowd-sourced themes - unfortunately, a lot of them are showcased on a discord server (sigh).

Here are direct links for a couple I really like:

• https://github.com/vacarotti/muOS_GamePal_Theme/releases/tag/Theme
• https://www.patreon.com/posts/pop-theme-only-104940129

There is a great collection of a ton of other themes in this repo: https://github.com/MustardOS/theme

Something important I did for a change in organization of Saves and Save States was this:

Go to Application > RetroArch > Settings > Saving and make the following changes:

• Set Sort Saves into Folders by Core Name to OFF
• Set Sort Save States into Folders by Core Name to OFF
• Set Sort Saves into Folders by Content Directory to ON
• Set Sort Save Sates into Folders by Content Directory to ON

Hit Save Configuration in the main RetroArch menu after this.

This will allow your saves/states to be retained in their System-based folders instead of emulator Core-based folders, so a file for a GBA game like Wario Land 4 will be saved as ../ROMS/MUOS/save/state/GBA/Wario Land 4 (USA).sate1

After some hours of gaming, I also found the designed shortkeys were pretty bad for handling Save States, and I just started using MENU + X > Save State/Load State to manage this type of thing via RetroArch. I found this a much more pleasant experience. But hey, its good to have both as option at the end of the day.

It requires wifi to be configured and on, but you can set up Retro Achievements within RetroArch if you have an account at https://retroachievements.org

You can do this by going to Apps > RetroArch > Settings > Achievements then put in your login information.

Please note that RA does not seem to cache any progress you make with achievements when you are not connected to wifi or if your connection is severed, so its a bit finnicky in that way.

muOS comes with some pre-existing bash scripts for backing up your fames, configurations, saves, and artwork. This is great, but these are all in different scripts each and also I've found in certain circumstances they can bea bit finnicky.

I whipped up https://github.com/RooneyMcNibNug/RG35XX-SP/blob/main/holistic_bkp.sh to be a single "good enough" script to backup the following (and only the following):

• Saves and States for any games
• Screenshots taken from all emulators
• All BIOS files you have on the device
• The main RetroArch configuration files

NOTE: These backups won't work directly with the backup manager, but its nice to have these files without a zip to quickly also use locally if you'd like (on the pC you are backing them up to). You can always throw them back into the microSD manaully or send them Over The Wire.

I know this is a clamshell and inherently a great way to keep the screen safe from damage, but I can be clumsy sometimes.. I don't want to buy a case really, so I thought about even just getting some decent fabric and sewing it up into a little pouch for the XX-SP. For now, I am using a beer coozie for when I throw this in my backpack. No, I'm not joking. This doubles as a decent layer of protection for the hardware while also keeps my fingers dry if I want to have a can of something while gaming 😄

This device is great. I recommend picking one up if you have the means.

muOS really does make a difference so far. Its feels lightweight in comparison to the stock firmware, and also gets rid of some of the big gripes I have with the defaults on the stock one as well - things like the awful "HD" rendering on by default for games, which makes everything look articifially smoothed out (like spilled milk or something..)

All in all the muOS configurations and gaming itself feels more polished.