How to Install GammaOS on the RG405M & RG405V

The Anbernic RG405M and RG405V are excellent emulation handhelds held back by mediocre stock software. Installing GammaOS replaces that stock Android with a debloated, performance-tuned LineageOS build — and the whole process takes about 30 minutes. This guide walks through every step.

What you need before starting

• An Anbernic RG405M or RG405V with a fully charged battery
• A PC (Windows, macOS or Linux) with a data-capable USB cable
• The correct GammaOS release package for your exact model, downloaded from the official GitHub releases page
• A backup location (SD card or PC) for your ROMs, BIOS files and save states

Step 1 — Back everything up

Copy your ROMs, BIOS files, save files and save states to your SD card or PC. Then eject any microSD card from the device — leaving a card inserted during flashing can cause problems.

Step 2 — Choose Full or Lite

GammaOS comes in two editions. Full includes Google Play Services and the Play Store, which most people should pick. Lite excludes Google entirely for extra performance headroom and ships with the Aurora Store instead. Both editions perform far better than stock firmware.

Step 3 — Unlock the bootloader

1. Boot the device into Android normally and connect it to your PC via USB.
2. Open a command prompt or terminal and run adb reboot bootloader.
3. The device reboots and shows “fastboot mode” next to the Anbernic logo.
4. Confirm the unlock on the device — on the RG405M the confirm button is the Home/Back button on the front bottom-left corner.
5. When you see “Unlock bootloader success!”, run fastboot reboot fastboot and wait until the screen says fastbootd.

Step 4 — Flash the partitions

Extract your downloaded GammaOS package. On Windows, double-click FlashPartitions.bat. On macOS or Linux, open a terminal in the GammaOS folder and run sh FlashPartitions.sh. Let the script run to completion, including the cooldown timer at the end — do not disconnect the cable early.

Step 5 — Erase user data

Run the EraseUserData script from the same folder. You will see a wall of error messages — this is normal and they can be ignored. What is not normal is skipping this step: leftover stock data is the number-one cause of boot loops after flashing.

Step 6 — First boot

Press the power button. The device shows debug text about an unlocked bootloader and skipped verification — again, normal. The first GammaOS boot takes several minutes, then the Android setup wizard appears. Complete it, re-insert your SD card, restore your files, and the device drops you into the Daijisho launcher with RetroArch pre-configured.

If something goes wrong

That's the whole process. For device downloads, the compatibility table and 20 more FAQs, head back to the main GammaOS page.

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GammaOS Full vs Lite: Which Edition Should You Install?

Every GammaOS release page offers two downloads, and picking the wrong one means re-flashing later. The difference comes down to one thing: Google. Here is how the two editions compare in practice, and a simple rule for choosing.

The short answer

What each edition contains

Why Lite is faster

Google Play Services is not just an app store — it is a permanently running background framework that consumes memory and CPU cycles even when you never open the Play Store. On a device with 4 GB of RAM, that overhead disappears into the noise. On RK3566 handhelds with tighter memory, removing it produces headroom you can actually feel in heavier emulation.

What you give up with Lite

• No Google account sync — no Play Store library, purchases, or automatic app updates through Google.
• Some apps expect Play Services — most emulators run fine without it, but a few mainstream apps complain or lose features.
• Manual update habits — the included Aurora Store handles installs and updates well, but it is one extra thing to learn.

What you keep with both editions

Everything that makes GammaOS worth flashing is identical in both: the debloated LineageOS base, the Daijisho launcher, pre-configured RetroArch, quick-settings performance modes, controller layout tiles, and AdGuard DNS ad blocking. The choice is purely about the Google layer.

Can I switch later?

Yes — switching editions means flashing the other package, which wipes the device again. That is exactly why it is worth choosing deliberately the first time. Back up, pick using the rule above, and you will not need to revisit the decision.

Ready to choose? Grab the right package from the official download section and follow the step-by-step install guide.

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GammaOS Core Explained: Setup on Powkiddy, Miyoo Flip & More

GammaOS Core is the third member of the GammaOS family, and the most different. Instead of replacing internal firmware, it is a minimal Android 13 TV build — based on LineageOS — that runs on low-powered budget handhelds, often booting straight from an SD card. Here is everything worth knowing.

What makes Core different

The main GammaOS builds target Anbernic's mid-range hardware with a full Android 12 experience. Core goes the other direction: it is built for devices with weak chipsets like the Rockchip RK3566 and Allwinner A133P, with no touchscreen required. It has been heavily trimmed to reduce memory footprint — one release alone freed an additional 160 MB — and ships with RetroArch preinstalled and preconfigured.

Key features

• Minimal Android 13 TV base — designed for controller-first navigation, no touch needed
• Magisk root included — real system control out of the box
• Quick shortcuts menu — hold the power button for brightness, performance modes, controller settings and app-kill options
• Mouse emulation — Select + R1 turns your sticks into a pointer for apps that expect touch
• HDMI output settings — plug in a cable, pick your mode, reboot for a clean TV picture
• Relaxed scoped storage — easier file access than modern stock Android allows
• SD card boot on many devices — keep your internal firmware intact while trying Core

Supported devices

The SD card matters more than you think

Because many Core installs boot from SD, the card is your system drive. An A2 rating matters because it measures random read/write performance — exactly what an operating system does constantly — rather than the sequential speeds printed on the packaging.

Setup in brief

1. Download the Core release for your device from the official GitHub releases page.
2. Write the image to a quality SD card following the project wiki's bootable-card instructions.
3. Miyoo Flip only: install the Gamma Bootloader via the stock firmware first using the provided loader package.
4. Insert the card, boot, and land in a controller-ready Android TV environment.

Known limitations

Core is younger than the main branches, so check release notes: exFAT support needs a separate enable package, Bluetooth has been non-functional in some Allwinner betas, and keeping Wi-Fi on during sleep drains the battery. None of these are dealbreakers — they are the normal texture of an actively developed project.

Compare all three editions on the compatibility page, or grab Core directly below.

⬇ Download GammaOS Core

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7 GammaOS Tips & Hidden Features After You Install

Flashing GammaOS is only half the upgrade — the other half is knowing what it can do. These seven features are the ones new users most often discover weeks later and wish they had known on day one.

1. Match the performance mode to the console

GammaOS exposes three performance modes through quick settings tiles: Max Performance (everything at full frequency), Normal (scales with load) and Power Save (minimum frequencies for maximum battery). The trick is matching mode to workload: Power Save is genuinely enough for GBA and older systems and can dramatically stretch battery life, while Dreamcast, GameCube and PSP want Max Performance.

2. Long-press Home to save and quit any game

In RetroArch, holding the Home/Back button saves your state and exits — and the game resumes that exact state when you relaunch it. It works like a console quick-resume feature and removes any reason to leave the device running between sessions.

3. Remap ABXY from quick settings

Switching between Nintendo-style and Xbox-style button layouts is a quick settings tile, not a buried menu or a button combo. Your choice persists across reboots. The same tile row covers analog stick sensitivity, axis inversion and swapping the D-pad with the left stick — the last one is a lifesaver on the RG ARC.

4. Threaded video for Power Save mode

If you run demanding cores in Power Save mode, enable threaded video in RetroArch's video settings. It decouples rendering from the main emulation thread and smooths out frame pacing at low CPU frequencies. Newer GammaOS installs ship with it already enabled.

5. Ad blocking is already on — and adjustable

GammaOS ships with AdGuard DNS enabled by default, which silences ads in most free apps system-wide. If it ever interferes with an app, toggle it off under Settings → Network → Private DNS — no extra app needed either way.

6. Use Aurora Store even on the Full edition

Aurora Store is included as an alternative app source. Even Full-edition users benefit: it can install region-locked apps and works without signing into a Google account, which keeps a gaming device pleasantly anonymous.

7. Turn off Wi-Fi sleep drain

If your handheld loses charge overnight, the culprit is usually Wi-Fi staying active during sleep. Disable “keep Wi-Fi on during sleep” in network settings, or simply power off fully between sessions — with quick-resume save states (tip #2), you lose nothing.

New to GammaOS entirely? Start with the installation guide or the Full vs Lite comparison.

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Privacy Policy

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Terms & Conditions

By accessing and using gammaos.org, you agree to the following terms. They are short, plainly written, and worth the two minutes.

1. Nature of this website

gammaos.org is an independent, unofficial documentation and information website about GammaOS custom firmware. We are not the developer of GammaOS and we do not host firmware files. All download links point to the developer's official GitHub release pages.

2. Informational purposes only

All guides, compatibility notes, and troubleshooting content on this site are provided for general informational purposes. While we work to keep information accurate and current, firmware projects change quickly and we make no warranty that any content is complete, correct, or up to date at the moment you read it. Always follow the official README bundled with your download.

3. Assumption of risk

Flashing custom firmware modifies your device at a system level and carries inherent risk, including data loss, boot failure, and potential warranty implications. By following any guide on this site, you accept that you do so entirely at your own risk and that gammaos.org is not liable for any damage to your device or data.

4. Intellectual property

GammaOS is developed by TheGammaSqueeze and released under its own open-source terms. Anbernic, Powkiddy, Miyoo, and other device names are trademarks of their respective owners. Android is a trademark of Google LLC. Original written content on this site belongs to gammaos.org and may not be republished wholesale without permission.

5. No emulation content

This site does not provide, link to, or endorse the distribution of copyrighted game ROMs or console BIOS files. Users are responsible for ensuring any files they use with their devices are legally obtained.

6. Limitation of liability

To the maximum extent permitted by law, gammaos.org and its operators shall not be liable for any direct, indirect, incidental, or consequential damages arising from the use of this website or the software it documents.

7. Changes to these terms

We may revise these terms at any time by updating this page. Continued use of the site after changes are posted constitutes acceptance of the revised terms.

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Disclaimer

Read this before flashing anything. It is short and it matters.

Independent, unofficial website

gammaos.org is a fan-made documentation site. We are not affiliated with, endorsed by, or connected to TheGammaSqueeze (the GammaOS developer), Anbernic, Powkiddy, Miyoo, TrimUI, Google, or any hardware manufacturer. All product names, logos, and brands mentioned are the property of their respective owners and are used for identification purposes only.

Flash at your own risk

Installing custom firmware such as GammaOS involves unlocking the bootloader and rewriting your device's system partitions. Done incorrectly — or occasionally even done correctly — this can result in data loss, an unbootable device, or voided warranty coverage. Neither this website nor the GammaOS developer accepts responsibility for damage to your hardware. If that risk is not acceptable to you, do not flash custom firmware.

No warranty on information

Content on this site reflects our best understanding at the time of writing. Device support, installation steps, and features change between releases. The authoritative source is always the official GitHub repository and the README included with each release package.

Downloads

We do not host or modify any firmware files. Every download button on this site links directly to the developer's official GitHub release pages. We strongly advise against downloading GammaOS from any other source, including file-hosting mirrors, as such files may be tampered with.

ROMs and BIOS files

GammaOS ships with emulators only. This site does not distribute or link to game ROMs or BIOS files, and nothing on this site should be read as encouragement to obtain them unlawfully.

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