Zelda 2 I'd have to really study; if possible, I'll try to transfer the mechanics over.
----
Next out of the grabbag. So you possibly know about the Konami GB Collection (Color), many by
Rushiomatsu of Kirby border fame.
https://www.romhacking.net/hacks/6111/https://www.romhacking.net/hacks/6112/https://www.romhacking.net/hacks/6113/Soft reset issues and minor reset flicker bugs are patched out.
ex.

==>

(seems like everyone has this bug)

==>

(original has it too)
Then there's the missing games:

+

(other GB3 not shown)
And pressing select at each game title will not return you to Konami main menu either. But it will act like a d-pad option, behaving like original GB games also.
That's out of my kitchen sink. Patches shipped out for testing.
(although now I notice Gradius does not have orange loading flicker in original gbc. wonder where that came from)
Twinbee loading flicker is like that in original gbc too. Not sure what they had in mind with the blue palette switching.
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Ys 1 I really want to get back and add
Fray's portrait fixes. Plus
Datchy compatibility.
November 12, 2021, 08:57:24 pm - (Auto Merged - Double Posts are not allowed before 7 days.)
Falcom never makes anything easy.

Based on Fray's helpful information, black burn reduced to this:

which reveals some new hidden lighting.
Though now it literally requires un-burning all the font tiles and window trim. Which I have zero idea if it will affect anything else in the
entire game. Haven't done it yet as it's going to create a massive cross-compatibility headache with everyone's works (Japan font, Japan Datchy font, Spanish font, English font, Datchy + Spanish + cross-fixed font, Datchy + English + cross-over). Given the new findings, I'd be willing to do it but not that soon.
If it's safe, still requires someone to add new color to each affected portrait. I think everyone uses a unique palette which adds some sanity.
(suggestions on recolor? Fray?)
You can use this
on top of your patched rom to apply
Fray's Olman's + (partial) un-black fix.
https://github.com/minucce/workbox/raw/4c573e7b9582a1f28e91aa64a0613c0dc53dd29c/box16/hidden.ips