Glitch City Laboratories Forums

Lab γ: Video Games and Glitches Discussion => Video Game Glitches Discussion => Topic started by: Evie the Bird Mother ❤✿ on August 30, 2017, 07:56:11 pm

Title: Serious emulation problem with Monster Race (GB)?
Post by: Evie the Bird Mother ❤✿ on August 30, 2017, 07:56:11 pm
A while ago now I picked up this interesting Japanese game called Monster Race (もんすたあ★レース) in which you collect and race with monsters.

It turns out saving twice in that game (or even once) on both BGB(!) and VBA may cause a 'glitch' that creates a Glitch City and allows you to skip parts of the game, but I haven't been able to get that to work on a real Game Boy Advance SP or a physical Super Game Boy.

(https://media.giphy.com/media/3ov9jXU9bdDDi1IYCI/giphy.gif)

Ryuto138 has a TAS video that exploits the error to complete the game quickly.

https://www.youtube.com/watch?v=xJ9RqF8KGV4
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Parzival on August 31, 2017, 06:54:30 am
Might be a game-specific problem. Or just s**t code. I'll do some testing.
EDIT: This works on shitty emulators, hyper-accurate emulators, and emulators that force GB mode. Strange.
EDIT 2: aaaaaand i've raped the game. Not a suprise.
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Evie the Bird Mother ❤✿ on August 31, 2017, 12:25:40 pm
Might be a game-specific problem. Or just s**t code. I'll do some testing.
EDIT: This works on shitty emulators, hyper-accurate emulators, and emulators that force GB mode. Strange.
EDIT 2: aaaaaand i've raped the game. Not a suprise.

Thanks for testing! Yeah, I thought so too after it worked on BGB (otherwise known as an accurate emulator). Which emulators did you try may I ask?
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Parzival on September 01, 2017, 08:16:10 am
Gambatte, mGBA, LameboyDS, and DSBoy.
All of them had the problem. I also tried a friend's flashcart on his GBA SP, and it was present there, albeit inconsistent. This kinda makes me believe that a bad dump was hashed as the known-good.
(Also, if you can find the item in the starting town and use it, you can see your expanded party. lel)
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Wack0 on September 01, 2017, 02:01:47 pm
I also tried a friend's flashcart on his GBA SP, and it was present there, albeit inconsistent.

I'm assuming you mean a GB(C) flashcart like the old parallel-port ones from Bung?

By the way, another possible cause of this could be some form of anti-flashcart protection that is hit by emulators too.
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Parzival on September 01, 2017, 07:13:59 pm
I also tried a friend's flashcart on his GBA SP, and it was present there, albeit inconsistent.
I'm assuming you mean a GB(C) flashcart like the old parallel-port ones from Bung?
It's some weird-ass GBA cart... "GBA Movie player" or some such. Takes those stupid fucking CompactFlash cards. He's got an 8MB... drive? card? in it, but he says it takes max. 256MB ones, and he can't find one that size.
Looks like this, but the card's flush with the cart end.
(https://i.imgur.com/Tx56XD0.jpg)
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Wack0 on September 01, 2017, 07:48:27 pm
I also tried a friend's flashcart on his GBA SP, and it was present there, albeit inconsistent.
I'm assuming you mean a GB(C) flashcart like the old parallel-port ones from Bung?
It's some weird-ass GBA cart... "GBA Movie player" or some such. Takes those stupid fucking CompactFlash cards. He's got an 8MB... drive? card? in it, but he says it takes max. 256MB ones, and he can't find one that size.
Looks like this, but the card's flush with the cart end.
(https://i.imgur.com/Tx56XD0.jpg)

So, it's a cart that runs in GBA mode, and probably uses a GB emulator then.
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Caveat on September 02, 2017, 08:59:27 am
Maybe it only works on normal Game Boys, like that glitch where the player's sprite gets corrupted when using an Escape Rope?
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: ISSOtm on September 02, 2017, 10:36:52 am
Given that I own a DMG, a CGB and a GBASP plus two flashcarts, I'd be eager to test this - however I don't have the necessary ROM.
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Wack0 on September 02, 2017, 10:46:43 am
Given that I own a DMG, a CGB and a GBASP plus two flashcarts, I'd be eager to test this - however I don't have the necessary ROM.

You can't search the Internet for it?
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: ISSOtm on September 04, 2017, 03:30:46 am
I tried but it yielded no valid result (now I get why, I typo'd the name)
This didn't work on my GBC, and Torchickens mentioned it didn't work on her GBA SP, so I believe the cart was faulty.
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Parzival on September 04, 2017, 08:48:43 am
Maybe it only works on normal Game Boys, like that glitch where the player's sprite gets corrupted when using an Escape Rope?
I tested in BGB in CGB mode, and it's present.
I tried but it yielded no valid result (now I get why, I typo'd the name)
This didn't work on my GBC, and Torchickens mentioned it didn't work on her GBA SP, so I believe the cart was faulty.
The glitch doesn't work? In that case, BGB is s**t, VBA rules, and everyone's dead.
Seriously though, if even BGB fucks it up at 99.97% or so accuracy, there's something horribly wrong.
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Evie the Bird Mother ❤✿ on September 04, 2017, 10:07:27 am
I didn't think about that, maybe the ROM I used was indeed a bad dump (causing the errors on an emulator) and my physical cartridge (being official) was a good dump hence didn't have the glitch on GBA SP and my physical SNES/Super Game Boy.

This is the MD5 checksum of the ROM I used on emulator.
6C124C8C7FBF7D330EBC2F06DAD7E270

DAT-o-MATIC says this is a trusted dump (http://datomatic.no-intro.org/?page=show_record&s=46&n=0818), but with the information now maybe that was a false positive.
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Wack0 on September 04, 2017, 10:36:31 am
I didn't think about that, maybe the ROM I used was indeed a bad dump (causing the errors on an emulator) and my physical cartridge (being official) was a good dump hence didn't have the glitch on GBA SP and my physical SNES/Super Game Boy.

This is the MD5 checksum of the ROM I used on emulator.
6C124C8C7FBF7D330EBC2F06DAD7E270

DAT-o-MATIC says this is a trusted dump (http://datomatic.no-intro.org/?page=show_record&s=46&n=0818), but with the information now maybe that was a false positive.

Actually, it seems as if that ROM is a bad dump.
DAT-o-MATIC says that two dumps were made in 2014 and both have MD5 hash of 3029C962C483DF174FC6F5C9202326E3.
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Parzival on September 04, 2017, 11:21:41 am
I didn't think about that, maybe the ROM I used was indeed a bad dump (causing the errors on an emulator) and my physical cartridge (being official) was a good dump hence didn't have the glitch on GBA SP and my physical SNES/Super Game Boy.

This is the MD5 checksum of the ROM I used on emulator.
6C124C8C7FBF7D330EBC2F06DAD7E270

DAT-o-MATIC says this is a trusted dump (http://datomatic.no-intro.org/?page=show_record&s=46&n=0818), but with the information now maybe that was a false positive.

Actually, it seems as if that ROM is a bad dump.
DAT-o-MATIC says that two dumps were made in 2014 and both have MD5 hash of 3029C962C483DF174FC6F5C9202326E3.

Welp. My tests are out the window too, then. I have Torchicken's hash.
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Krys3000 on September 04, 2017, 04:55:40 pm
Hey, I have one of those GBA Movie Player! Good times playing NES on my DS Fat.
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Wack0 on September 07, 2017, 09:43:33 am
I finally took a look at the "bad dump", turns out it's not really a "bad dump", someone modified the ROM.

Entry point jumps to 0:00e0, which is just nops in the good dump, but this space was used to add the following code:


ld a,0
ld [$6000],a
ld a,$30
ld [$6000],a
jp $0150


This code makes no sense, the header says it uses MBC1, where $6000 is a 1-bit wide register that flips between two different banking modes. Maybe this is for flashcart compatibility?

In addition, a ld a,1 got patched to ld a,0 at 00:024C, and again at 01:488E.

Finally, the header checksum got patched.
Title: Re: Serious emulation problem with Monster Race (GB)?
Post by: Parzival on September 08, 2017, 08:05:07 am
Well then... we have our answer.