Hello, could someone help me to unpack/repack this kind of archive, been struggle for months now but can't find any tool for it. This come from Ys IX Monstrum Nox game.

https://drive.google.com/file/d/1OV8hxadmTlA0vMaXBNboBZMKH16_IKj5/view?usp=drive_link

Edited January 26Jan 26 by petermike867

On pc version game doesn't has this archive, all files unpacked

11 minutes ago, MrIkso said:

On pc version game doesn't has this archive, all files unpacked

thanks you for the reply, but i want to edit ps4 version. 😞

please, anyone.

I'd suggest to search for 'vfs' in the Zenhax archives, 153 results. Maybe there's some useful hint among them?

On 1/27/2026 at 10:53 PM, shak-otay said:

I'd suggest to search for 'vfs' in the Zenhax archives, 153 results. Maybe there's some useful hint among them?

Unfortunately, what I read on the Zenhax archive wasn’t of any help; they also couldn’t figure out the compression used by the VFS3 file.

1 hour ago, petermike867 said:

they also couldn’t figure out the compression used by the VFS3 file.

too bad. Then a comtype scan could come in handy. But it could get somewhat boring because you'll need to check 100 and more resulting extracted files manually in a hex editor for a hit,

I initially analyzed the file and found instances of F1N Headers (46 6C 4E), of which there are 196 in the file. I managed to find several matching addresses in the index. The analysis is in its early stages, so that's all I can share for now.

10 hours ago, zbirow said:

I initially analyzed the file and found instances of F1N Headers (46 6C 4E), of which there are 196 in the file. I managed to find several matching addresses in the index. The analysis is in its early stages, so that's all I can share for now.

tysm for your time analysing this!

any progress on this?

looked into it and seems to be using the same format as Ni No Kuni 2 & Killer7 but with a different compression than zstd or zlib (the str offset is 0 and the decompression dictionary offset is now the str offset, also the compression id is kinda just random)

Edit: I think I mixed up some fields, probably zstd without decompression dicts but with encryption

Edited 3 hours ago3 hr by NeoGT404

I'm thinking it's encrypted so I'll need the game executable

Here's a hexpat:

struct Str {
    u32 l;
    char v[l];
};

struct de {
    u32 crc;
    s32 id;
    s32 pid;
    s32 nid;
    u32 dc;
    s32 u1;
    u32 fc;
};
bitfield fle {
    bool zstd : 1; // otherwise zlib
    bool compressed : 1;
    padding : 3;
    unk1 : 1;
    padding : 10;
    s16 zstd_dict_id;
};
struct fe {
    u64 off;
    u64 zs;
    u64 us;
    u32 crc;
    u32 fid;
    fle fl;
    u32 did;

    char start[4] @ (parent.do + off);
    char end[4] @ (parent.do + off + zs - 4);
};
struct ce {
    u32 s;
    u32 cs[s / 4];
};

bitfield fl {
    padding : 4;
    bool chunks : 1;
    bool zstd_dicts : 1;
    padding : 26;
};
struct a {
    char magic[4];
    fl fl;
    u32 v;
    u32 dc;
    $ += dc * 0x1C;

    u32 fc;
    u64 fso = $;
    u64 do = fso + fc*0x28 + 0x18;
    u64 chnkdo @ (do - 0x18);
    u64 decdo @ (do - 0x10);
    u64 stro @ (do - 8);
    u64 so = stro;
    if (so == 0) so = decdo;    

    $ = so;
    u32 fsc;
    Str fstrs[fsc];
    u32 dsc;
    Str dstrs[dsc];

    $ = chnkdo;
    u32 chnkz;
    u64 ep = $ + chnkz;
    ce ce[while($ < ep)];

    de de[dc] @ 0x10;
    fe fe[fc] @ fso;
};

a a @ 0;

1 hour ago, NeoGT404 said:

I'm thinking it's encrypted so I'll need the game executable

Hi, tysm for your time working on this, here is the game executablemain.zip