Emulation Homebrew neogeo for old 3ds users

zzcx88 · Oct 11, 2026

Neo Geo games at full speed on the Old 3DS.

How it works: install the neo3ds launcher once, convert your Neo Geo game zips (MAME romsets) into game files with the web converter, put them in /neo3ds/games/ on the SD card and pick a game from the list. When a new version comes out, you only reinstall the launcher; your game files keep working.
If you prefer, the converter can also build one CIA per game, each with its own HOME menu icon and banner.

Web converter (runs in your browser, your files never leave your PC):
https://zzcx88.github.io/neo3ds/

Offline converter (Windows, Linux and macOS, all with a window and a command line) and the launcher:
https://github.com/zzcx88/neo3ds/releases/latest

New in 1.4:

Games on the arcade (MVS) BIOS start in a few seconds: the board check (the green screen) now runs fast in the background
Fixed Metal Slug 2 and Last Blade 2 seeming to freeze on that green screen for about a minute (1.4.1)

New in 1.3:

Launcher favorites: press SELECT (or tap the * next to a game) to add it; Left/Right switches between All and Fav
Raster effects: games that change the picture partway down the screen now draw correctly (Neo Turf Masters' water, Neo Drift Out's stage starts and curves)
Linux and macOS converters now open in a window, like the Windows app
Faster conversion, and slightly smaller game files

Also: full screen mode, bottom screen off button, save states (3 slots per game), arcade service menu with saved settings and high scores, region choice (Japan brings back the blood in Metal Slug), button remapping per game (including A+B, C+D), turbo, and batch conversion.

Running at full speed on my Old 3DS: KOF '95, '96, '97, '98, '99, 2000 and 2002, Metal Slug, X, 3 and 5, SVC Chaos, Samurai Shodown V Special, Neo Turf Masters and Neo Drift Out.
Others have reported KOF 2003 and Garou at 60 fps, and Metal Slug 4, Neo Bomberman, Street Hoop, Shock Troopers and Top Hunter running fine.

Battery is about 5 hours from a full charge on my Old 3DS (middle brightness, Wi-Fi off).

Setup, the full compatibility list (282 romsets) and how it fits into the Old 3DS's memory:
https://github.com/zzcx88/neo3ds
Compatibility list: https://zzcx88.github.io/neo3ds/compat.html
Changelog: https://zzcx88.github.io/neo3ds/changelog.html

Cascarajito · Oct 11, 2026

Playing NG games on an o3DS would be epic. I wish something like an FB Alpha port for 3DS exists for playing SEGA arcade games and CPS1-3 games

ber71 · Oct 12, 2026

Thanks.
if i understand correctly his is a kind of injector tool, to a homebrew emulator.
May i ask, why not promote this to a full-fledged emulator? Some basic ui, mainly for selecting the game, would suffice.

zzcx88 · Oct 13, 2026

ber71 said:
Thanks.
if i understand correctly his is a kind of injector tool, to a homebrew emulator.
May i ask, why not promote this to a full-fledged emulator? Some basic ui, mainly for selecting the game, would suffice.

The PC step is there because the bigger games don't fit in the Old 3DS's memory as they are.
The converter decrypts and compresses them first, and that would take far too long (or not fit) on the 3DS itself.

But a launcher is doable
install one app, copy the converted games to a folder on the SD card, and pick them from a list.
I'll look into it.
You'd still convert on the PC, but without installing a CIA per game.

Osakasan · Oct 13, 2026

Alright, this is interesting to say the least. I have my o3ds here at work, so i'll do some testing.

zzcx88 · Oct 18, 2026

1.1.0 is out!

@ber71 the launcher is in: install neo3ds-launcher.cia once, copy the converted games to /neo3ds/games/ on the SD card, and pick them from a list. No CIA per game needed anymore (that still works too).

Also new:
- Save states, 3 slots per game (bottom screen or SELECT+L / SELECT+R)
- Service menu + backup RAM, so arcade settings and high scores are kept
- Region choice: Europe/Asia, Japan or USA (Japan brings back the blood in Metal Slug)
- Convert several games at once
- Fixed Metal Slug's music dragging and Aero Fighters 2/3's music stopping

Rebuild your games with the new converter to get the new features.

https://github.com/zzcx88/neo3ds/releases/tag/v1.1.0

Cascarajito · Oct 19, 2026

zzcx88 said:
1.1.0 is out!

@ber71 the launcher is in: install neo3ds-launcher.cia once, copy the converted games to /neo3ds/games/ on the SD card, and pick them from a list. No CIA per game needed anymore (that still works too).

Also new:
- Save states, 3 slots per game (bottom screen or SELECT+L / SELECT+R)
- Service menu + backup RAM, so arcade settings and high scores are kept
- Region choice: Europe/Asia, Japan or USA (Japan brings back the blood in Metal Slug)
- Convert several games at once
- Fixed Metal Slug's music dragging and Aero Fighters 2/3's music stopping

Rebuild your games with the new converter to get the new features.

https://github.com/zzcx88/neo3ds/releases/tag/v1.1.0

Can I set the BIOS to Japanese AES?

Osakasan · Oct 20, 2026

zzcx88 said:
1.1.0 is out!

@ber71 the launcher is in: install neo3ds-launcher.cia once, copy the converted games to /neo3ds/games/ on the SD card, and pick them from a list. No CIA per game needed anymore (that still works too).

Also new:
- Save states, 3 slots per game (bottom screen or SELECT+L / SELECT+R)
- Service menu + backup RAM, so arcade settings and high scores are kept
- Region choice: Europe/Asia, Japan or USA (Japan brings back the blood in Metal Slug)
- Convert several games at once
- Fixed Metal Slug's music dragging and Aero Fighters 2/3's music stopping

Rebuild your games with the new converter to get the new features.

https://github.com/zzcx88/neo3ds/releases/tag/v1.1.0

Oh man! Much, MUCH better like this.

Trevor_2012 · Oct 20, 2026

Thank you very much; will there be a fullscreen mode and an option to turn off the bottom screen?

zzcx88 · Oct 21, 2026

Trevor_2012 said:
Thank you very much; will there be a fullscreen mode and an option to turn off the bottom screen?

Both fullscreen mode and the option to hide the bottom screen will be included in the next release.

ber71 · Oct 21, 2026

Managed to mass convert the 282 ROMs from mame, in a legacy windows 8.1. No need for w10/11

The converter skipped 40 ROMs as expected.
Just one rom failed to convert. Dragonsh.zip caused this error: "sequence contains no matching elements". Tried from different sources.

Osakasan · Oct 21, 2026

I have a full mame romset i'm trying to convert, but the batch converter stops at certain games:

neonopon.zip
neopong.zip
neothund.zip
ngem2k.zip

It says that it can't convert them because they're not MAME roms. Any way to make the converter to continue after it encounters one of these errors?

zzcx88 · Oct 21, 2026

Trevor_2012 said:
Thank you very much; will there be a fullscreen mode and an option to turn off the bottom screen?

1.2.0 is out with both: a full screen mode (Key config → Screen → Full) and a button to turn off the bottom screen (the small ⏻ at the top right; touch the screen to turn it back on).https://github.com/zzcx88/neo3ds/releases/tag/v1.2.0If you use the launcher, installing the new launcher CIA is enough.
Your .neo3ds files work as they are.

Post automatically merged: Oct 21, 2026

Cascarajito said:
Can I set the BIOS to Japanese AES?

Yes. When converting, pick Region: Japan and System: AES.
It uses neo-po.bin (the Japanese AES BIOS) from your neogeo.zip.
If that file isn't in the zip, it falls back to the European one.

Post automatically merged: Oct 21, 2026

ber71 said:
Managed to mass convert the 282 ROMs from mame, in a legacy windows 8.1. No need for w10/11
The converter skipped 40 ROMs as expected.
Just one rom failed to convert. Dragonsh.zip caused this error: "sequence contains no matching elements". Tried from different sources.

dragonsh is an unfinished prototype from a development board.
Its sound program and samples were never dumped, so it has no sound even in MAME.
The converter crashes on the missing sound ROM instead of handling it. I'll fix that and see if it runs (silently).

Post automatically merged: Oct 21, 2026

Osakasan said:
I have a full mame romset i'm trying to convert, but the batch converter stops at certain games:

neonopon.zip
neopong.zip
neothund.zip
ngem2k.zip

It says that it can't convert them because they're not MAME roms. Any way to make the converter to continue after it encounters one of these errors?

Which converter did you use: the web converter, the Windows app, or the command line?Those four are homebrew titles that aren't in the converter's game list, so they can't be converted right now.
But the batch should skip them and convert the rest.
The Windows app and the command line do that.
The web converter stops at the first one it can't convert, which is a bug I'll fix.Until then, taking those zips out of the batch will get you through.

Trevor_2012 · Oct 21, 2026

Thank you very much, it works perfectly in full screen.

Osakasan · Oct 21, 2026

zzcx88 said:
Which converter did you use: the web converter, the Windows app, or the command line?Those four are homebrew titles that aren't in the converter's game list, so they can't be converted right now.
But the batch should skip them and convert the rest.
The Windows app and the command line do that.
The web converter stops at the first one it can't convert, which is a bug I'll fix.Until then, taking those zips out of the batch will get you through.

There's a Windows app? O_o

I didn't notice, i was using the web converter, now that there's a launcher i wanted to finally start using this on my work 3DS.

Ok, i'll look for the app tomorrow. Thanks!

Post automatically merged: Oct 22, 2026

Ok, i was finally able to test it properly and it's so smooth! I wasn't expecting Art of Fighting 3 to run properly at all.

I've loaded a few random games (Super Dodge Ball, Over Top and a couple more) and none of them gave me any trouble.

Amazing work. I hope we end up getting something like this for CPS boards.

DominoBright · Oct 22, 2026

Ah, so that's how they get high speed!

I really do like this better than RA FBNeo/FBAlpha on 3DS though. Even on the New2DS, I gotta hit the frameskips on games like these.

Garcimak · Oct 22, 2026

this feel so cool to play with the 2DS mushy d-pad and buttons

Osakasan · Oct 22, 2026

Garcimak said:
this is so cool to play with the 2DS mushy d-pad and buttons

If you're good enough with the slide pad, it's the closest option to that Neo Geo Pocket feel.

zzcx88 · Oct 23, 2026

DominoBright said:
Ah, so that's how they get high speed!

I really do like this better than RA FBNeo/FBAlpha on 3DS though. Even on the New2DS, I gotta hit the frameskips on games like these.

Thanks for the feedback!
In the attached screenshots, is the area that should be water showing up as grass in neo3ds?

DominoBright · Oct 23, 2026

zzcx88 said:
Thanks for the feedback!
In the attached screenshots, is the area that should be water showing up as grass in neo3ds?

Yup. Filenames are what is being used (though FBNeo was played on PC, but FBAlpha showed water on 3DS before).

Emulation Homebrew neogeo for old 3ds users

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