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Retro Handheld Front Ends and Firmware: ES-DE, Daijishō, ROCKNIX, Knulli and More, Kept Up to Date

Every front end and firmware for Android and Linux retro handhelds: what each one costs, which devices it runs on, and what changed last.

Victor · Updated Nov 11, 2026

The ES-DE, ROCKNIX, Knulli, MustardOS, NextUI and spruce logos in a grid of six tiles
ES-DE, ROCKNIX, Knulli, MustardOS, NextUI and spruce, six of the projects this page keeps up with. Logos: their makers

There’s a folder on my KONKR Pocket Advance called Front-Ends, and it holds four different ways to start the same games. ES-DE, Daijishō, iiSU and Socket. Same emulators underneath. Four completely different front doors.

That’s all a front end is, the menu you see before the game starts. On an Android handheld you pick one like an app. On a Linux handheld you usually pick a whole new operating system, and the menu comes with it.

Both worlds move fast, and older guides age badly. ArkOS is gone. MinUI is frozen. muOS goes by MustardOS now. So this page keeps track of all of it, and it changes whenever they do.

What’s new?

November 10: ZNeko 0.6.23

ZNeko just changed where your artwork comes from. ZNeko 0.6.23 asks iiDB first. That’s iiSU’s own artwork database, and iiSU’s app just started pulling from it too. SteamGridDB and ScreenScraper are the backups.

The better part is that you can now pick the art yourself, inside the app. You can browse the artwork and screenshots with previews, and hand-pick the icon, logo and hero image for a whole system. ZNeko remembers your picks for future iiDB scrapes, so a game it matched to the wrong thing stays fixed. There’s a switch to turn the sound clips off, too.

Your folders can look the part, as well. There are new icon sets for them, including a light and a dark one from iiDB, so they can match a light or dark theme.

November 9: iiSU Alpha 0.0.7.5

Two-screen handhelds get a lot of fixes in this one. Quit a game on one, and iiSU could come back on the wrong screen. Or it would pop up on top of a game that was still running. iiSU Alpha 0.0.7.5 fixes both. Docking and undocking shouldn’t leave you staring at a blank screen anymore, either.

The fun part is the artwork. Scraping, if the word is new to you, is how a front end looks up each game online and fills your library with box art. iiSU can now pull that art from a source called iiDB. You get a gallery of icons, logos, backgrounds and screenshots to browse. It’ll even fetch short sound clips for your games, and you can listen before you pick.

And if iiSU ever closed on you right as a game started, the memory problem behind that is fixed. A new setting can pause animated art during launches, too.

November 7: spruceOS 4.6

Touch screens get some love. spruceOS 4.6 lets you tap to launch a game, swipe through your library and type on an on-screen keyboard. There’s a new Kid Mode too, a locked-down setup built around picking a game and nothing else. The Powkiddy V90S joins the device list, and the GameMT E5 Plus gets early support.

November 7: Recalbox 11 reaches three more handhelds

Recalbox 11 now runs on the Retroid Pocket Nova, the Anbernic RG35 and the RG35XX Pro. The catch is that it’s for Patreon backers only until Recalbox 11 is finished, and there’s no date for that. So far the team’s happy with games up to GameCube on the Nova and up to PlayStation 1 on the two Anbernics.

Older updates (3)
October 24: MustardOS 2606.0 Andromeda

The current MustardOS adds Bluetooth. Don’t read the 2606 as a date, by the way. It came out in October.

October 13: NextUI 6.15

If you’ve got one of Anbernic’s RG35XX-style handhelds, here’s a new option. NextUI used to be a TrimUI thing, and version 6.15 brings it over to that whole family.

September 30: ES-DE 3.5

If you’ve got two screens, ES-DE 3.5 lets you choose which one a game launches on, per system or per game. It can also pull game videos from TheGamesDB now.

What’s the difference between a front end and firmware?

A front end is a menu, and firmware is the whole operating system. A front end doesn’t play anything by itself. It shows your games with their box art, and when you pick one, it hands the game to an emulator, the program that actually pretends to be the old console.

Firmware goes deeper. It replaces what your handheld boots into, usually from an SD card, and brings its own menu along. Think of the difference between changing your phone’s home screen and installing a different operating system on your PC.

Stock menus are why people bother. Here’s my KONKR’s own library with nothing done to it. Those tiles are supposed to be box art.

Hands holding a grey KONKR Pocket Advance on a red table, its game library showing rows of blank tiles with no box art
The stock AYASpace library on my KONKR Pocket Advance, before any front end got involved.

Which Android front end should you get?

The one that matches how many games you’ve got and how many screens you’ve got. All of these launch the emulators you install yourself, so trying a second one doesn’t undo the first. Tap a logo for the details.

Two newer ones aren’t on the cards yet. Boxshelf turns your collection into a 3D shelf of boxes you can flip open, and it’s brand new. Argosy is built around RomM, a game library you host at home, so it’s really for people who already run one.

Which firmware works on your handheld?

Start with your device, because that settles most of it. Here’s who lists what.

Your handheldFirmware that officially lists it
Anbernic RG35XX Plus, H, SP, 2024, Pro; RG40XX; RG CubeXX; RG34XX; RG28XXROCKNIX, Knulli, MustardOS, NextUI, spruceOS (needs a second card), Batocera (RG40XX V; its wiki names the rest)
Anbernic RG353 and RG503ROCKNIX, Batocera, dArkOS, Recalbox (RG353 only), AmberELEC test builds
R36S and similarROCKNIX, Knulli; AmberELEC test builds; many clones are experimental
Miyoo Mini and Mini PlusOnion, spruceOS, Allium
Miyoo FlipKnulli, spruceOS
TrimUI BrickNextUI, Knulli, MustardOS, spruceOS
TrimUI Smart ProNextUI, Knulli, MustardOS, spruceOS, CrossMix
Retroid Pocket 5, Flip 2, MiniROCKNIX, Knulli (early builds), Batocera, Armada
AYN Odin 2 family and ThorROCKNIX, Batocera, Armada
Powkiddy RGB30ROCKNIX, Knulli, Batocera, dArkOS, spruceOS
Steam DeckRetroDECK, EmuDeck, ES-DE, Batocera, Recalbox

Two gaps stand out. ROCKNIX doesn’t list a single Miyoo or TrimUI handheld, and MustardOS has no Miyoo in its current list either.

Found yours? Tap its firmware below.

If you want PC game ports on a retro handheld, PortMaster lists ROCKNIX, Knulli, MustardOS and dArkOS as fully supported.

Knulli or MustardOS?

It comes down to sleep and Bluetooth. Knulli wants you to shut down rather than sleep, because suspend drains the battery fast on most of its devices, and it spells out what Bluetooth does: controllers and audio both work, as long as the controller has a PC mode. MustardOS lets the power button sleep, but Bluetooth only arrived with its current release, and it prefers a freshly flashed card for updates.

Pick the one whose trade-off you can live with. Both lists cover the RG35XX family, and an SD card is cheap enough to try each.

ROCKNIX or Knulli?

ROCKNIX if you’ve got something newer or something Snapdragon, Knulli if you’ve got one of the devices it was made for. Their cards have the details, including what’s different under the hood.

RetroDECK or EmuDeck on a Steam Deck?

RetroDECK is one self-contained app, and EmuDeck is an installer that sets up each emulator separately. Both projects describe themselves that way, so pick the one that sounds like you.

How should you set up your SD card?

Let the firmware have the whole card, and don’t panic when it takes it. If your card suddenly looks like it’s lost all its free space, or Windows can’t read half of it, that’s normally on purpose. Each firmware’s card above says what it does to yours.

How do you make one your home screen, and undo it?

Through Android’s own settings. Search for Default Home App, pick your front end, and your handheld boots straight into it. Changing your mind is the same trip in reverse.

Can you go back to the stock system?

Usually, and rule one is to keep your original SD card. On Anbernic’s H700 handhelds the stock system lives on a card, and NextUI even installs onto it. Delete one file, dmenu.bin, and you’re back to stock.

Onion leaves the Miyoo firmware alone by design. The one to think twice about is ROCKNIX installed to internal storage on a Snapdragon handheld. It’s optional, it shrinks Android, and it wipes your Android data like a factory reset. There’s an uninstall option, but your data won’t come back with it.

Knulli and MustardOS don’t spell out the way home for most devices, which is one more reason to hang on to that first card.

Which projects have stopped?

ArkOS, JELOS and MinUI, so be careful with old guides. If one tells you to install ArkOS, you want dArkOS instead. Same developer, and the old one was retired at the end of 2025. JELOS shut down in 2024, and ROCKNIX carried on from there. AmberELEC is a stranger case. Its stable release hasn’t moved since February 2023, yet test builds were still coming out in October.

Don’t trust GitHub’s “latest” label on these, either. Knulli’s old repository is archived and still shows August 2025, while the real release sits in a new one. Onion’s release tagged “latest” is actually a beta. Batocera’s GitHub releases stop in 2021, and it’s on 43.1. Go by each project’s own page, or by the cards up above, which keep up.

Which one should you try first?

Whichever costs you the least to be wrong about. On Android, a front end is an app, so you can install another and lose nothing. That’s how a handheld ends up with four of them in one folder. On Linux, a spare SD card is the entire experiment.

On the shelf

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