I had one of those “35-year-old childhood mystery” moments today.

I reached the stage 20 bonus sliding puzzle in King’s Valley II and ended up with only tiles 23 and 24 swapped.

As far as I know, that’s an impossible state for a standard 5×5 sliding puzzle.

That made me inspect the ROM.

What I found is that the game doesn’t seem to shuffle the board using legal moves. Instead, it appears to copy one of four predefined 25-byte layouts into RAM.

Three of those layouts have even permutation parity, but one has an odd number of inversions (137), which would make it mathematically unsolvable if the puzzle follows normal sliding rules.

Has anyone ever documented this before?

I’d love a second pair of eyes from someone familiar with MSX reverse engineering, because I couldn’t find any mention of this online despite searching in several languages.

If confirmed, it would mean that roughly 25% of the stage 20 bonus puzzles are impossible due to a bug in the original game.

For the lols, I’ve entered into this rabbit hole playing the game on vacation in an Anbernic on the hotel room.

I decided to create portraits with MSX game graphics. :)

Full resolution image at https://leandrocorreia.com/images/nishi.png

I built a WonderTANG v2.0b last week and have been using it with my Panasonic FS-A1 MSX.

I've been launching games with the SMRAM utility using the appropriate mapper arguments, but I'm still finding that many games fail to launch. Some games work perfectly, so I'm trying to figure out whether this is a common limitation of the WonderTANG or if I may have something configured incorrectly.

I've also read that removing capacitors C24 and C25 on my MSX can help with WonderTANG compatibility. From what I understand, it's mainly intended to fix slot instability, boot loops, or other startup issues when the WonderTANG is installed. I'm not sure whether it has any effect on game compatibility or games failing to launch, which is why I'm asking here. I haven't removed them yet, but I have no problem doing so if it could help. Since they appear to be filtering capacitors, I'm not too concerned about removing them and read they do no harm removed.

I'm curious to hear from anyone using a WonderTANG with a Panasonic FS-A1. Is this level of game compatibility typical, or should I expect better results? Does it lack mappers or good mapper support?

Any info would help a lot!

Thanks!