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About the Game

Fushigi no Dungeon: Fuurai no Shiren GB: Tsukikage Mura no Kaibutsu, translated as Mystery Dungeon: Shiren the Wanderer: The Monsters of Moonlight Village, is a roguelike game developed by Aquamarine and published by Chunsoft, apparently released back in 11/22/1996. The game follows Shiren the Wanderer, and his talking weasel Koppa. The game has also gotten some ports/re-releases on Windows and Android. And there really isn't anything I can say past that, the game was only released in Japan, and there's really not much info about this game. The RTA leaderboards don't even have any runs on the Gameboy version. Luckily, this game is buggy so it won't matter for me.

Game objectives

Emulator used: Bizhawk 2.6

  • CGB in GBA mode is enabled for console verification.

Categories

  • Aims for fastest completion of the game
  • Executes arbitrary code
  • Corrupts save data
  • Some luck manipulation

Comments

The run is fairly short, so there isn't too much to comment on. The key exploit used is simply the L/R|U/D glitch. Essentially, the game doesn't handle L/R and U/D inputs correctly; often they will freeze the game, but sometimes they will cause ACE. This movie specifically uses the combination L/R/D to cause ACE at EDF0 (echo RAM for CDF0). I use my player name to store most of the payload, however, I simply don't have any bytes that can cause any jumps. That's where luck manipulation comes into play. The game stores 4 bytes for RNG at D601-D604. The game uses rTIMA (somewhat similar to rDIV, but much more restrictive for manipulation) for seeding the RNG, and uses a fairly complicated LFSR to cycle through RNG.

Stage by stage comments

Save file creation

I need to create a save file to really do anything, which can be quickly done. It also needs to be the 3rd save file, the 1st one won't work. I hard reset once the main save file is actually made (although before the backup is made; this causes the game to create the backup save after the hard reset is done, which changes RNG). As a note, the game doesn't seem to have any soft reset, and going back through the main menu without resetting is much slower, and will simply not work for my purposes anyways (due to the game splashing FFs in a huge chunk of RAM I need to slide past). As a note, this reset is why I need to use the 3rd save file, as the game will load the 3rd save file's data by default, and will only load the other save files if they actually go into the game (which I don't want to do).

RNG Manip/Name/ACE

This is where the main improvement from the previous comes in. After the reset, I manipulate for a fairly specific RNG combination. From my RNG log of all possible initial seeds:
Tima0: 01 | Tima1: C8 | Tima2: E9 | RNG: 02 D5 87 C9
The main prize in this particular seed is $02 right before a $D5 -> $C9 combination. I then proceed to rename myself, which will write the following code into memory:
ld de,$7C1C ; credits location
ld a,e ; a = $1C
Afterwards, I need to flash the rename screen again. This will clear out a troublesome buffer of my name, leaving in some $88 bytes. I then just have to wait for a counter to tick down to $00. This ends up changing it to $01 (and stays that way), and also places a $28 byte two bytes away. This results in the following opcode.
ld bc,$2800
bc is now $2800, which is perfect since this is around the general area where I need to write to trigger a bankswitch. I can press L/R/D now, which now executes the payload.
Now remember that RNG seed? This is at the end of a payload, which ends up being the following in assembly:
ld (bc),a ; bankswitch to bank 1C
push de ; (sp) = $7C1C
add a
ret ;  pc = 1C:7C1C, credits are located here
No inputs are needed for the cutscene, so input is ended once ACE is executed.

Samsara: Since I've already confirmed sync and legitimacy when I encoded this over a month ago, and since nobody else seems to want to even look at this run, I'm just going to go ahead and rescind my encode claim and accept it to Vault as an improvement to the published run.
fsvgm777: Processing.

TASVideoAgent
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xxezrabxxx
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My dumbass got the aspect ratio wrong. Accidently put 1400 instead of 1200 in the resizing when dumping Link to video edit: author made his own encode with the correct aspect ratio
I like to comment on submissions and look around the site. You have probably seen me before (if you have been around for a while) either on the site, Discord, or any other social media. I recently took up making temporary encodes for new submissions. Also, I never forget to greet Tompa wherever I find him! "when resyncing stuff sucks it's called Resuccing" - EZGames69 “If an emulator stops being accepted to the site it should be called an emuLAMEr” - EZGames69 "oh no discord, everything I say will now be logged forever, sdfsdf, time to hide" - Masterjun "just had to give therapy to a taxi with daddy issues" - psx Current Projects: Mother 3 (Streaming entire process live!) https://twitch.tv/xxezrabxxx
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And here I thought Link to the Past was the most broken result of left+right input out there.
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Given you trigger ACE by pressing L/R or U/D (so probably can trigger ACE almost everywhere), would you ever make a playaround of this game?
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jlun2 wrote:
Given you trigger ACE by pressing L/R or U/D (so probably can trigger ACE almost everywhere), would you ever make a playaround of this game?
I wouldn't say "everywhere". As I said:
going back through the main menu without resetting is much slower, and will simply not work for my purposes anyways (due to the game splashing FFs in a huge chunk of RAM I need to slide past)
So if I ever enter the game, which I would likely need to do create a bigger payload, I would need to reset and do special preparation to execute this bigger payload (probably possible?). Even then, I don't think this is a very good game to have a play around for, I could go do a playaround of Gen 2 Pokemon and it'd likely be much better (like actually having English characters). Still, I wouldn't leave this entirely out of consideration...
Post subject: we in there, boys
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Post subject: Movie published
TASVideoAgent
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This movie has been published. The posts before this message apply to the submission, and posts after this message apply to the published movie. ---- [4412] GB Fushigi no Dungeon: Fuurai no Shiren GB: Tsukikage Mura no Kaibu "game end glitch" by CasualPokePlayer in 00:14.82