Emulation Homebrew Yokoi: Game & Watch / SM5xx Based LCD Handhelds Emulator

SenseiFromClubPenguin · Wednesday at 10:46 AM

This is a simple port of the Yokoi emulator for 3DS / Android created by RetroValou that can play most Game & Watch games, clones, and with beta support Tiger LCD handhelds and David & John games (hypothetical modern LCD console with same processor). You need to build an Android based rompack in addition to running the .nro , more info in the README

Also supports flip grips with 90 and 270 degree screen rotation for the dual screen / vertical games. Check it out here: https://github.com/1timewire1/Yokoi_Game_-_Watch_emulator_switch/tree/switch-port

jeferey · Wednesday at 7:34 PM

Ohhh amazing!!

SenseiFromClubPenguin · Friday at 1:22 PM

If every system's games are working aside from the open source David & John games, I created a patch that let's you patch the missing assets into your rompack. Simply copy your current rompack into the folder with this python script and run it. The script will make a backup of the original pack, and produce a new one with the D&J assets included. Once you verify the new pack is good, you can delete the backup. There's more info in its included README

Post automatically merged: Friday at 2:41 PM

I just pushed a new build, 1.0.1, that adds support for custom segment visibility and background colors (per request)

mathew77 · 2026-08-29T18:58:28+0100

@SenseiFromClubPenguin
Thank you for the Switch port!..

Could you please help me a little: when I try to build my own "yokoi_pack_rgds.ykp" file from my very own MAME ROMs, I've got that error:

Code:

python convert_original.py --target rgds

Traceback (most recent call last):
  File "..\CONVERT_ROM\source\generate_games_path.py", line 15, in <module>
    from source.games_path_utils import GameEntry, write_games_path
ModuleNotFoundError: No module named 'source.games_path_utils'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "..\CONVERT_ROM\convert_original.py", line 19, in <module>
    from source.generate_games_path import generate_games_path
  File "..\CONVERT_ROM\source\generate_games_path.py", line 20, in <module>
    from games_path_utils import GameEntry, write_games_path
ModuleNotFoundError: No module named 'games_path_utils'

All the prerequisites (Inkscape, tex3ds, dependencies) are done, MAME rom in .CONVERT_ROM\rom\roms\ folder in a zipped form.

SenseiFromClubPenguin · 2026-08-29T19:32:55+0100

mathew77 said:
@SenseiFromClubPenguin
Thank you for the Switch port!..

Could you please help me a little: when I try to build my own "yokoi_pack_rgds.ykp" file from my very own MAME ROMs, I've got that error:

Code:

python convert_original.py --target rgds Traceback (most recent call last): File "..\CONVERT_ROM\source\generate_games_path.py", line 15, in <module> from source.games_path_utils import GameEntry, write_games_path ModuleNotFoundError: No module named 'source.games_path_utils' During handling of the above exception, another exception occurred: Traceback (most recent call last): File "..\CONVERT_ROM\convert_original.py", line 19, in <module> from source.generate_games_path import generate_games_path File "..\CONVERT_ROM\source\generate_games_path.py", line 20, in <module> from games_path_utils import GameEntry, write_games_path ModuleNotFoundError: No module named 'games_path_utils'

All the prerequisites (Inkscape, tex3ds, dependencies) are done, MAME rom in .CONVERT_ROM\rom\roms\ folder in zipped for.

Weird. I can't help a ton until Tuesday, but first I'd try again with the original repo's converter script for Android in case maybe an edit I did trying to fix the David & John games messed something up (if this works, the output will be missing the D&J games assets, but you just need to use the patch attached above after to re-add those if you want them. That patch is confirmed working)

mathew77 · 2026-08-29T20:01:26+0100

@SenseiFromClubPenguin
Wow, thank you!.. With the RetroValou's scripts it's all good for now, hooray!..

Here's my screenshots from the Switch with the v1.0.1 (2.3.1 base) version, works good:

..btw In my humble opinion, just in case, a whole process to compile ykp seems a little bit overcomplicated — all the Inkskapes, devkits, pythons, mame archives, zips, tex3ds, necessary artworks, etc etc etc. These games are hella old, and nobody will care if one will attach already pre-compiled DB with all the compatible games at once near the homebrew.
Bu-u-ut it's just my opinion, and nothing more.

SenseiFromClubPenguin · 2026-08-29T20:07:55+0100

mathew77 said:
@SenseiFromClubPenguin
Wow thank you!.. With the RetroValou's script it's all good for now, hooray!..

Here's my screenshots from the Switch with the v1.0.1 (2.3.1 base) version, works good:
View attachment 588286 View attachment 588287

In my humble opinion, just in case, a whole process to compile ykp is a little bit overcomplicated, all these Inkskapes, dekits, pythons, mame archives, artworks, etc, these games are hella old, and nobody will care if one will attach already compiled DB with the homebrew. Bu-u-ut it's just my opinion, nothing more.

That's good to hear! I'll have to revert those scripts in my repo when I can. Yeah, I'm not a huge fan of the rompack system either, but I wasn't sure what to change it to so I just kept their system in. If you have a better idea of how to handle it, I could try to adapt to that (also any other feature requests let me know, I'm gonna look into filters next based on a request)

Emulation Homebrew Yokoi: Game & Watch / SM5xx Based LCD Handhelds Emulator

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