[lancuster]

For sure, many of those who collect new games on the NES (any NES games) encountered this type of images that run only on special emulators. VT03 games have a much more advanced palette and sound channels (some even support WAV samples). But with all this, they are still the same NES rom. Also, I found a program somewhere that allows you to turn any NES image into a VT03 compatible rom. The code doesn't change much, but something makes the game work differently, the graphics are separated into a basis and mask.

Based on this, I had a question: if there is a possibility to convert NES to VT03 - is there any possibility to do the opposite? How many interesting games we could get, compatible with the original NES engine.

[KingMike]

I suppose that is quite similar to a Game Gear-to-SMS hack.

A lot of manual effort changing code, with some content downgrade for whatever used the extended capabilities. (was it just extended palettes or tilemapping or what?)

[Psyklax]

From what little I've seen of this, the answer is yes, you could turn them into a regular NES ROM, though as KingMike said, it's a bit like Game Gear to SMS. If you load a VT03 game into a normal emulator, the colours are all messed up, so a bit of hacking would allow you to fix that.

But...

Find me one VT03 game that's actually worth doing it. All of those games are simple things made by Chinese programmers and put on plug-and-play devices. They're interesting as a curiosity but then I'd rather see them how they're supposed to be, in that case. I can't think of any game that's worth the trouble of fixing the colours.

[lancuster]

From what little I've seen of this, the answer is yes, you could turn them into a regular NES ROM, though as KingMike said, it's a bit like Game Gear to SMS. If you load a VT03 game into a normal emulator, the colours are all messed up, so a bit of hacking would allow you to fix that.

As far as I understand, some add-in code is used, which forces the game to run in the desired mode. Plus the graphics itself is divided into a base and a mask. If you try to remove the extra graphics - it doesn't really help because in VT03 mode there is NO switching banks graphics - switching is carried out from the outside.
If you try to run the game on 176 or 4 mapper - the banks will not switch. About palette... I don't say anything.

Find me one VT03 game that's actually worth doing it. All of those games are simple things made by Chinese programmers and put on plug-and-play devices. They're interesting as a curiosity but then I'd rather see them how they're supposed to be, in that case. I can't think of any game that's worth the trouble of fixing the colours.

I can be wrong, however, there are quite good games, and there are a lot of them:

October 26, 2019, 05:19:43 pm - (Auto Merged - Double Posts are not allowed before 7 days.)That's what I got just after removing the duplicate graphics and assigning the game mapper MMC3.

After the first run, banks does not switch, as well as the palette, the background scrolls vertically.  However, after the game over, the graphics and palette can switch, but the screen flickers, as if it runs over one another.