Does anyone know if there's ever been a conversion of Armadillo/Mario IV to standard mapper 4 (or if one would even be feasible)? AFAIK all dumped multicarts containing the game use weird registers to "mimic" mapper 118 behavior, but aren't outright mapper 4 conversions.

Recently, I've been attempting to research a specific set of VT02 games from an unclear developer. The games in question are Fruit Pig, Eeeck! A Mouse, Echo Chamber, Trounce, and a Sudoku game. Since there's no clear development company, however - nor are there dozens of games to work off of, like the unknown JungleTac-affiliated developer - I can't really compile it into a wiki page or anything (it's currently just a footnote on the Nice Code Software article as "unconfirmed games", which I somewhat doubt the status of). As such, I thought I'd compile what I've gathered into a list here, so the information is at least out there:

-For a brief gameplay summary (save for self-explanatory Sudoku): Fruit Pig is a simple "catch the fruits" game, Eeeck! A Mouse is a Whac-A-Mole game, Echo Chamber is a clone of Simon (i.e. the board game), and Trounce is loosely based on the Japanese plug & play "Popira". All of them use music from the Famicom game Parasol Henbee.
-Fruit Pig is by far the most common, followed by Sudoku. Both titles appear on many multicarts from the mid-2010s onward (e.g. Super Game 360-in-1, CoolBoy 400-in-1), with Fruit Pig also appearing on the common 200-in-1 plug & play. The other three games are far less common, but sporadically show up on some later 2010s releases.
-With the exception of Sudoku, all of the games only use the d-pad during gameplay; not using the A or B buttons. This suggests to me they were designed for a Dance Dance Revolution mat or some similar special controller.
-Further indicating the above, the first version of the "Double Dance Mania" plug & play features Echo Chamber and Trounce (but not the other titles). The currently dumped revision of Double Dance Mania is the "Technolight Edition", however, which includes different games. Oddly, on the back of the back, the game screenshots are recreated with vector graphics (see https://i.ebayimg.com/images/g/lygAAOSwDiZk~LWv/s-l1600.jpg).
-There is a variant of Fruit Pig where the player is replaced with a penguin for some reason (see https://www.youtube.com/watch?v=7jS2uOK52-A&t=385s). This may be a Cube Technology hack of the game.
-In my most bizarre find, there is a Russian handheld called the "Exeq Toy" that features what appear to be advanced VT368 hacks of these games. I was able to confirm a game called "Crazymouse" is a conversion of Eeeck! A Mouse (see https://youtube.com/watch?v=ciqfovpXP_Y), but could not find clear enough screenshots/videos of the others. Presumably, going by the game list, "Sudoku 368" is Sudoku, "Fruit New" is Fruit Pig, and "Simon" is Echo Chamber; there's no obvious title listed for Trounce.
-The other unknown games listed on the Exeq Toy are Raptor Rage (port of a mobile game?), Winmine (Minesweeper?), Arameo, Funny Quest, IdolumMaze, Biomatch, and Angel. It also features a game titled "Angry Birds 368", which is a hack of the Super Angry Birds bootleg; as to if that indicates the unknown company made that game as well, who knows.
-Just by fate I suppose, there is a more common (?) revision of the Exeq Toy that features a generic VT02 menu without these games; so tracking a system down would be quite difficult.
-In a recently compiled list by Taizou, he labels the titles as possibly being "Spritemind" games (see https://museum.12bit.club/viewer/ods.php?f=Subor_Q6_game_list.ods). I am assuming this refers to Shenzhen SpriteMind Software Co., Ltd., who is credited on some mid-2010s multicarts (namely the Super Game 150-in-1 with the Sonic splash screen). I could ask Taizou what makes him theorize Spritemind is the developer, but haven't as of currently.
-I have the source GIF that was used as reference for Fruit Pig's character sprite. No idea where the picture in itself is from, but the sprites were modeled after this character.

It's an issue with releases of FCEUX earlier than the recommended version 2.6.2; the Duck 3D Blast ROM relied on PRG-RAM, which earlier emulators did not support in this form. The 86-in-1 re-converted the hack to not use PRG-RAM; I have released a new 64-in-1 ROM revision using the "fixed" version of Duck 3D Blast.

It appears to be the Master System version running on the homebrew SMSAdvance emulator. It's quite interesting regardless, as I've never seen a single-cartridge GBA bootleg running a Master System game like that (it was common practice for NES games through PocketNES, but not other emulators).

No problem, glad it was of interest.

Here are restorations of some of the "Qi Sheng Long" variants of Nice Code games. These releases never had copyright notices originally; however, a few games in this library originally had two-player modes, which were removed in the currently dumped revisions. Additionally, two games had extended titles: "Indreak" was originally called "Indreak in the Conduit", and "The Worms" was originally called "The Training Camp of Worms". I'm not sure exactly why the titles were simplified, though data for the original logos still exist in the ROM.

In total, I have restored seven of the Qi Sheng Long games: including the aforementioned Indreak in the Conduit and The Training Camp of Worms, alongside Bear vs. Thief, Cool Baby, Doll, Fairy, and Monster Ball. "Bubbles Puzzle" also has a two player variant, though I was unable to restore that one. I used footage of the Japanese "FC Home 88" console as reference.

Here are five of the "Super" hacks seen on some early 90s multicarts - Super Donkey Kong 3, Super Galaxian, Super Pac-Man, Super Pooyan, and Super Star Soldier. These are pretty simple hacks conceptually; Super Pac-Man greatly increases Pac-Man's speed (similar to the arcade "speed-up chip" hack), while the other three just increase the player's bullet speed/power. Some multicarts also feature a "Super Star Force", though I haven't included it here for the simple reason that I can't figure out what it actually changes (outside of some nasty title screen coloring...)

Normally, these games are built into the original versions in code (i.e. unhacked Pac-Man runs on the same file as Super Pac-Man); I wasn't able to rip them for the longest time because of this. However, I came across a couple multicarts which run the "Super" games separately from the originals, allowing them to be extracted.

Here are MMC3 conversions of the two Ocean-published Bubble Bobble games: Rainbow Islands and Parasol Stars. Note that these were PAL-exclusive releases originally, and have slight graphics issues on later levels if run as NTSC (which isn't a result of the mapper hack).

The method in which I was able to convert these games is quite bizarre. I found that four Ocean releases - Rainbow Islands, Parasol Stars, The Addams Family, and Cool World - feature near-identical opcodes and code structure. There is a fan-made Addams Family MMC3 port by "infidelity" which included documentation, so I used that as reference for Rainbow Islands/Parasol Stars; alongside some code from a bootleg Cool World conversion.