[Gary_Oak]

Wolchild is a platforming game originally released by Core Design in 1992 for the Commodore Amiga and Atari ST. It was eventually ported to other gaming platforms such as the Sega Genesis, Sega CD, SNES and Master System/Game Gear. In my eyes, it's an hidden gem of a game.

Redbook audio aside, the Mega/Sega CD version of Wolfchild is essentially identical to the Genesis version, save for on minor quirk...

In the Sega CD version, "Stage 2: Dense Jungle" has a missing background layer (layers?). When comparing with the Genesis version, you can tell this didn't seem intentional at all, and it might have happen either due to a rushed port job or... plain old forgetfulness?

Assuming both Genesis and Sega CD versions of the game share the same code, how hard would it be to create a patch the ports the missing background layer (layers?) found in the Genesis version back into the Sega CD version?

Sega Genesis



Sega CD

[4lorn]

I know the Amiga version was the original one, but don't know which came first, the Genesis or Sega CD port. Curiously, did anyone back in the day when print was king noticed or mentioned this in reviews? It doesn't seem like any of the so-called "retro lovers" on YouTube noticed or mentioned the difference between the Mega and Sega CD backgrounds, either.

Anyway. Looking at the ISO the missing graphics are actually there, including the Dense Jungle tiles... The issue is they're simply not loaded into the level's memory. Compare the level through a VDP Viewer output:

Genesis version
Sega CD version

But even more interesting is that they must have been expected to be, because there are tilemap definitions for the scrolling background: the level will automatically display any graphic referenced in its tilemap, just not the correct one. I assume this must have been some mistake on Core Design's part.



I've tracked down one of the possible strings that affect this by running breakpoints on the Genesis version, then comparing it with the CD version's code. The CD version uses the same code *twice*, presumably because unlike the Genesis version, the Dense Jungle is composed of two levels and not just one. Regardless, the changes I've made definitely require a lot more fiddling. The missing tiles are loaded into memory but they're not quite where they should be and they corrupt other stuff. Not sure how to go about this one for now.

August 23, 2021, 07:50:18 am - (Auto Merged - Double Posts are not allowed before 7 days.)So, update: I got it working.

I'm just playtesting it now to check if there are any side effects (doubt it), and then I'll have to scour the nets for releases and make IPS patches.

I'll update the post with more info on the issue that was present in the game as soon as possible.

[Gary_Oak]

Hey there 4lorn,

Thank you for looking into this matter so thoroughly, I honestly didn't imagine it would have caught anyone's interest given the obscurity of the game.

So, from what I understand, the tileset data was there all along (in the Sega CD version) but it was never loaded due to a programming oversight on Core's end?

[Anime_World]

If tiles still present in CD files, you just need to modify DMA Length of first write or DMA Address of second write.

[4lorn]

Hey there 4lorn,

Thank you for looking into this matter so thoroughly, I honestly didn't imagine it would have caught anyone's interest given the obscurity of the game.

So, from what I understand, the tileset data was there all along (in the Sega CD version) but it was never loaded due to a programming oversight on Core's end?

Yes. I looked at the game's TOC and noticed a disparity between the level data size, and the amount of data it was supposed to read. Just increasing the value of how much it should read fixed it. A single byte change, actually, but one that's been neglected for 28 years. Everything points to it just being an oversight on their part.

[Gary_Oak]

Yes. I looked at the game's TOC and noticed a disparity between the level data size, and the amount of data it was supposed to read. Just increasing the value of how much it should read fixed it. A single byte change, actually, but one that's been neglected for 28 years. Everything points to it just being an oversight on their part.

That byte change you mention, do you think it could be easily rectified with the use of a Game Genie/Pro Action Replay code or would it require use of an actual patch?

[4lorn]

That byte change you mention, do you think it could be easily rectified with the use of a Game Genie/Pro Action Replay code or would it require use of an actual patch?

I rarely make use of GG/PAR codes, so I wouldn't know how to create one for it.

But I have released a patch for the US, EU and JP versions of the game here on RHDN.

[KingMike]

My understand is you can't use a real GG or PAL with a Sega CD game.
Putting one in would make the console select the cartridge slot as the active media port.