A few more fixes for some shoddily-coded Nice Code games:
*Coast Guard (a Canyon Bomber hack) appears to have had some graphic tiles shifted during development, which was not corrected via code; resulting in the life icon not displaying, and the "Time Over" and "Game Over" text displaying incorrect tiles. I have attached corrected versions below for both copyright revisioins.
*Fated Pirate has its music played back terribly; restarting the main audio channel when beginning a game, while continuing to play the backing tracks (resulting in greatly unsynced music). To fix this, I simply zeroed-out the code that restarts the main sound channel. I also applied this fix to the "Corsair" variant, which features different (and slightly more intuitive) control mapping.

Here are the unique games ripped from the "G3" 800-in-1 handheld. This console had a staggering amount of undumped Nice Code variants, including some that were entirely undocumented. Some of the more notable titles include "Fishing Challenge" (an advanced variant of Atlantic Fishing Tournament 2005), "Boat-Race-Pika" and "Teletubb" (uncommon Inventor hacks), and a few games which were previously only known to appear in Timemax-affiliated game sets. In addition to these games, a lot of the variants here are quite subtle; most of them have been added to the wiki, though I can clarify further information if needed.

The extracted games are attached below; I have also included a few ROMs that are altered to restore copyrights and whatnot.

Thank you for providing it. I managed to identify every Famicom/NES ROM within the code (sifting through loads of junk data), mainly done by just searching for common .nes file sizes (e.g. 25k, 41k). Games of particular note include the following:

*Three uncommon Inventor hacks: Air Raider, Dream Rapid, and a variant of Rush Hour featuring motorcycles (whereas the prior known version uses cars). The early version of Boat Race mentioned a few posts back is also present here in working order.
*Anger Bird, Khresna, and Upin & Ipin Adventure 3, three hacks which are affiliated with the "Play Vision Portable" systems.
*The 8-bit version of Waixing's Explorer (AFAIK, the last remaining undumped VT02 game in the set), as well as an MMC3-based version of Tank. Unfortunately, both ROMs do not run standalone; I assume this is initialization-related, though I could not determine a fix at a cursory glance.

Some additional technical notes that I found interesting:

*As mentioned in MAME's notes, remnants of what appears to be a Linux system are scattered across the SD card; with the NES ROMs haphazardly thrown in alongside the Linux data.
*Every ROM contains space for an iNES header, though in some cases it is overwritten with other data, presumably used by the VT02 menu system.
*Some of the games are duplicated multiple times across the SD card contents. While some duplicates are merely unaltered ROMs, others seem to be in varying states of removing the games' copyright information.
*All of the games are either NROM or MMC3, without support for CHR-RAM; which is to be expected of a VT02 console, but still a bit jarring given its SD card compatibility. There are quite a few MMC3 conversions on here as a result, including some games that are not commonly converted (e.g. Kero Kero Keroppi 1, Tetsuwan Adam).
*The ROM of Fish War features a Nature Color Game copyright, but it was blanked out via PRG (because of course it was). I did attempt to restore the notice, but it required more guesswork than usual...
*The ROM of Bolt Action is massively overdumped, and inexplicably, appears to have overwritten the data of "Mechanical Invader", a Nice Code game that is almost completely undocumented. The CHR is largely intact, though no portions of the PRG are present.

I have attached the most notable games below. I will likely compile the mapper hacks at a later date; if not a full release of the extracted contents. _{(Also note that with all of that, I still have no idea what "Video Player" was supposed to be...)}

This is more of an irrational rant than anything, but I'll offer some ROMs at the end for your troubles. There is a specific VT369-based game set that I periodically look around for, used across multiple handheld systems; it can have either a 416-in-1 or 500-in-1 game count (both of which contain duplicate games). This set includes several rare, undumped games, most notably "Attack Force" and "Space War3", which are affiliated with the "ex-Sachen" developers. A video showing the full game list can be seen here: https://www.youtube.com/watch?v=wRXnr87Whes

A few months back, a "D12" handheld was added to MAME (ROM name "d12power"); going by footage online, this system contained the 416-in-1 set I was looking for. While the dumped revision uses the same menu layout, however, the entire game list was swapped out with more common/standard plug & play ROMs; excluding every game I was looking for. A handheld that featured the 500-in-1 set, the "D9", was also just dumped (ROM name "d9_500"); but similarly, its game list was substituted with an even more infuriating selection. All of the games are non-curated, run-of-the-mill crap, to the level of the first game being Super Chinese with its mirroring bit set incorrectly.

In terms of potentially finding the original revisions of these consoles, the only difference I can spot (outside of game list) is that the earlier versions use Cube Technology-style sampled audio in the menu systems, and have lowercase letters in their English font. The later/dumped versions use NES-capable music, and have an all-caps font. As it stands, though, the more interesting game set is still MIA.

The D12 does actually have a handful of less common games on it (the D9 does not), so I have attached extracts of those below. Boat Race does not work correctly here; it may need initialization or something similar. The console also has many, many repeated games with altered title screens per duplicate entry; these are technically somewhat rare to see, though I haven't bothered extracting them as of currently.

Does anyone have the extracted SD card contents of the "Retro Arcade FC A6Plus - 8Bt Game Console" (ROM name "a6plus")? According to MAME, the console uses a VT369 menu interface, but reads most of its games off of a MicroSD card. Going by a Reddit post, the games seem to be standard .nes files, albeit very poorly-named (https://www.reddit.com/r/Handhelds/comments/1bu06a1/what_the_heck_is_this_aliexp_mini_arcade_with_tf/).

If the game list beginning ~FA400 in the ROM is accurate, it appears that a number of games are rare (e.g. Air Raider, Pikachu5) or potentially undocumented (e.g. "Bomb-Mar", "Video Player"). The ROM itself does contain ~6MB of Nice Code games (some being Qi Sheng Long variants), but I did not see anything undumped at a cursory glance.

Thank you. The menu interface was modified from a preexisting handheld console (the "Game Prince RS-1" 152-in-1), and was altered solely through HEX data. As such, you will need the original Game Prince ROM in order to develop a menu based on it. There were several key points that had to be studied surrounding the menu, in addition to standard graphic editing (using programs such as YY-CHR):

*Replacing all games on the original console with the new games, which were pasted in via HEX. This also involves altering the linked areas for each menu option, under the Game Prince menu's custom format for reading games (detailed in the "linked menu studies" section in the attached .txt, from address #05E010 onward).
*Altering the titles in the selection menu. This is fairly easy to edit, but it reads the code in multiple areas of the ROM, and is sometimes out-of-order compared to the numerical list.
*Adjusting the amount of menu entries, since I didn't use all 152 game slots. Note that it's much easier to shorten the game count rather than increase it.
*Changing the color values of the preview images, which is controlled by a line below each preview icon's palette data.

I have attached a .txt that I wrote while studying the menu system, though some parts may be irrelevant or confusing; thus the greater description above.

Understood for the most part. I was able to follow your instructions, but I still could not conclude how to find what the replaced pattern is (in cases where it is not 20 F0 FF). Some of the ROMs read the $6100 instruction in places outside of the footer; Baseball has it at 7DF2 for example. Working off of HEX, I can just search [20 00 61] to find the code area.

I was able to fix all but four of the previously-unripped games (the missing ones being Baseball, Beach Volleyball, Ice Hockey, and Racing Rivalry). As I had mentioned before, there are a number of unused games on the Tetris system, though the majority have been dumped elsewhere (unaltered NES Tetris, VT03-based Bubbles and Horrible Area, commercial Data East games, etc). I somewhat expected to find greater unused contents here, as my (non-Tetris branded) copy of the console features undumped VTxx hacks in place of the Nanjing sports games; though they are not present in the code at all.

An improved bundle of games is attached below, pre-decoded and uncommon titles only; also attached is a better .txt summary for the sake of accuracy. I also restored some text in Forest Kid, though was unable to do so for Aether Puzzle.

Surprised to see these dumped, especially given I had only just learned of the Waixing copyright variants from the Zenex console. A few things of note that might not be obvious:

*It appears that some of the games, despite sharing Waixing titles, were substituted with Nice Code/Power Joy versions; this includes Archery, Backstroke, Goal Keeper, Shudu, Slots Machines, Star, and Triple.
*Could be coincidental, but something about the (previously-undocumented) "Butterfly" and "Play To Shoot" hacks strongly remind me of two other Waixing-derived Nice Code variants, Parkinof and Ranchboy. I think it's the color palettes and overall shoddier-than-usual quality that indicate this to me...
*Close Quarters does appear to have been an alternate copyright revision, but it only reads off of seven characters that are blanked out in the CHR; I can't conclude what it was meant to credit.
*I had previously noticed a discrepancy with the colors of Hitting (Magic Egg hack) between the Play Vision version and the prior-dumped Waixing version. This console seems to use the unaltered Play Vision ROM; showing that, between both versions, they merely swap the CHR color values rather than altering the actual palette. As to why they did this, who knows.
*Plush Dog has the dog-hitting sprite slightly altered, and appears to be a different revision in code otherwise.