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Reny_oiz, posted Thu Dec 08, 2022 11:02 pm (74506)

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how can I unpack the CGs and scripts of games made by Cybelle for example:
Gakuen heaven Okawari (ps2 version)
Piyotan ~Oyashiki Sennyuu?Daisakusen~
kanon

I have the files for the first two if you need them.

BloodRaynare, posted Fri Dec 09, 2022 12:07 am (74508)

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Please post the sample files here.

Reny_oiz, posted Fri Dec 09, 2022 7:54 am (74512)

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sure, here:
https://drive.google.com/drive/folders/1INjx4NxfWoRZ0VeSLIOPC_kcHSS8dNUP?usp=sharing

BloodRaynare, posted Fri Dec 09, 2022 11:11 am (74515)

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The PAK format itself was simple, these BMS scripts is enough:

cybelle_pak.bms

Code:

get FILES long
math FILES - 1

for i = 0 < FILES
   get OFFSET long
   putarray 0 i OFFSET
next i

for i = 0 < FILES
   getarray OFFSET 0 i
   math i   1
   if i == FILES
      get PAK_SZ asize
      xmath SIZE "PAK_SZ - OFFSET"
   else
      getarray NEXT_OFFSET 0 i
      xmath SIZE "NEXT_OFFSET - OFFSET"
   endif
   string NAME p "d." i
   log NAME OFFSET SIZE
next

Use QuickBMS to run the script.

However, the GC/graphic files are compressed and currently the algorithm is not known and at worst, it was proprietary which means someone will have to reverse engineer the game to figuring it out and it was no easy task and also time consuming depending how hard it was. The script files are somewhat readable though given that your hex editor supports Shift-JIS japanese characters.

Also, no actual filenames inside the PAK file, so the script will outputs the name as the sequential numbers.

Reny_oiz, posted Fri Dec 09, 2022 12:02 pm (74517)

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Thanks for the help.