Since the recent trend of code agents, it has become much easier to write applications on the platform with the framework I’m not familiar with.

It reminded me I still have a GameBoy Clone I bought 23 years ago, and after some research I found there is a device and a framework I could write GB games/applications with, so I decided to purchase the device and try it out.

After around 3 weeks of waiting, I received the device shipped from Ukraine.

I tried with multiple code agents (Claude 4.6, gemini 3.1 pro), let them read the library & docs, then made some PoC. The result looks fine:

A PoC Dialogue on a Gang Feng 2003 GB Boy (GameBoy Clone)
A PoC dialogue running on a Gang Feng 2003 GB Boy (GameBoy clone).

But since my GB clone is only Black & White, I started considering trying a GBC since I hadn’t had a chance to get one before.

After a few nights on auction sites I got one for around 7700 yen, and another one for 6000 yen on Mercari which needed the polarizer film fixed. (I also purchased a GBA SP along the way, but I’ll leave that for the next post.)

Before the later GBC arrived I did some research on Gemini and found the approach for replacing the polarizing film.

After gathering all the materials, I started the replacement on a workday night.

Before the operation, the GBC with a burnt screen (only started with a bubble in the middle):

a bubble in the screen
A bubble in the screen.

Peeling from the corner, I removed the polarizer film. But as Gemini mentioned, a hard layer of glue was left.

polarizer film removed
Polarizer film removed; a hard layer of glue remained.

I took kinda a long time using isopropyl alcohol and a flat plastic spudger to remove all the glue left.

I’m pretty sure the screen didn’t get scratched. Maybe.

polarizer film cleared screen
Screen after cleaning the glue with isopropyl alcohol.

The new polarizing film doesn’t have glue, and once installed, there seems to be no space between the front protective glass and the screen. And since there is a circle of double-sided tape around the frame, the polarizing film won’t move. I tried a few times to align it at the correct angle, but it still seems darker than the original.

polarizer film replaced polarizer film original
New polarizing film installed. The original.

P.S. Actually, when I was writing this, I found there are a bunch of videos on YouTube showing the process. I should have watched them before the change.

Meanwhile I also changed the shell into an eXtremeRate one, which feels lots better.

Afterwards I made a Bad Apple!! on this GBC with gbdk-2020 (which is a typical video for these retro devices). The process isn’t complex, spent most of the time aligning the frame, making the buffer frame correctly, and aligning the MIDI with the actual video.

The final video and code:

repo: nyanshell/bad-apple-gbdk

I also ran it on the GB Boy. Since the CPU was faster (5MHz vs 4.19MHz original GB), the video looks like 1.2x faster. (might add the video later)

Next stage: Game Boy Advance SP with EverDrive GBA PRO.