R36S Firmware and Custom OS: ArkOS, MinUI and More

The R36S is a great device out of the box. But a custom OS transforms it into a completely different beast. Better performance, cleaner menus, more features, and a level of customization that stock firmware will never achieve.

I've tested every major custom OS for the R36S and I'll walk you through each one: What it does, who it's for, and how to install it. Four names come up most often (ArkOS, muOS, MinUI and Knulli), but only ArkOS runs on the R36S: the other three target other handhelds. For the R36S, the maintained options today are the dArkOS-based images (dArkOSen, dArkOSRE) and ROCKNIX.

Stock OS vs Custom Firmware: What's the Difference?

• Performance: Custom firmwares use better optimized emulators.
• Interface: Stock menus are functional but ugly. Custom OSes look better and navigate faster.
• Features: Save states, rewind, fast-forward, shaders — all limited or missing in stock.
• Updates: Custom firmware communities actively push updates. Stock firmware gets abandoned by the manufacturer.

The Big Four: ArkOS, muOS, MinUI and Knulli

ArkOS: The Gold Standard

ArkOS is the most popular custom firmware for the R36S, and for good reason. It strikes the perfect balance between features and usability. If you're unsure which OS to install, start here. One caveat: ArkOS is no longer maintained (last release on July 31, 2025); its author replaced it with dArkOS, available for the R36S as dArkOSen or dArkOSRE.

• EmulationStation frontend with box art and game descriptions
• RetroArch backend with dozens of emulator cores
• Save states, rewind, fast-forward, shaders, themes
• PortMaster: Play PC indie games natively (Cave Story, Stardew Valley)
• RetroAchievements with WiFi dongle

Installing ArkOS — Step by Step

1. Download the R36S image from the ArkOS R3XS GitHub page (the community ArkOS image for the R36S by AeolusUX, archived since its last release of November 7, 2025)
2. Download and install Rufus or Win32DiskImager (Windows) or ApplePi-Baker (Mac); avoid balenaEtcher, which the dArkOS developer advises against
3. Prepare a micro SD card — minimum 32GB, recommended 128GB
4. Open your flashing tool, select ArkOS image, select SD card, start writing (3-5 minutes)
5. Insert SD card into slot 1 of the R36S, power on, wait for first boot (2-3 minutes)
6. Copy games into the corresponding console folders

muOS: The Elegant Alternative

Important: muOS does not run on the R36S; its official device list only covers some Anbernic and TrimUI handhelds. muOS is newer than ArkOS, but has quickly built a loyal fanbase. Lightning-fast boot in about 5 seconds. Excellent N64 performance. Active Discord community with responsive developers.

MinUI: The Zen Option

Important: MinUI does not run on the R36S; its device list covers Anbernic, Miyoo, TrimUI and a few other handhelds, and the project is archived. MinUI is for people who want to turn on their device and play. No themes, no achievements, no shaders, no settings menus with 47 options. Just games. Ideal for kids — there's nothing you can accidentally break.

Performance Optimization Tips

N64

1. Switch to the parallel-n64 core in RetroArch
2. Set resolution to native (320x240) instead of upscaled
3. Disable texture filtering for speed boost

PSP

1. Use PPSSPP standalone instead of RetroArch core
2. Set rendering resolution to 1x
3. Enable frameskip to 1-2 frames

Related: worried about fakes? Read our R36S Original vs Clone guide — with real factory photos of the V21/V30 boards — or get an original R36S here.

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