Looking for a tool or script that unpacks data from Project IGI .res with filenames as well as a file format specification.

projectigi_res.rar

Here you go: https://github.com/smiRaphi/UniPyX (https://github.com/smiRaphi/UniPyX/commit/0dd34b6b7b17b13cb47467a6f519ab9ccabbaf23)

Format:

struct b {
    char bn[4];
    u32 size;
    u32 unk1;
    u32 aligned_size;
    if (aligned_size != 0) u64 ep = $ - 0x10 + aligned_size;
    else u64 ep = $ + size;

    match(bn) {
        ("ILFF"):{
            ep -= 0x10;
            char type[4];
            b b[while(($+0x10) < ep)];
        }
        ("NAME"): char name[size];
        ("BODY"): u8 data[size];
    }
    $ = ep;
};

b b @ 0;