XeNTaX

Hi Hello, I come from a distant part of the internet looking for some assistance.
So Metal Slug 3 was ported to the PS2. Kinda common knowledge. All the files are kept inside 6 ".afs" files (I'm able to extract these easily), but inside the AFS files are .pal, .pak, and .adx files (including a SND file.)
I'm able to play the ADX and SND files fine with PSound, but not do anything with the pak files. Most of them have a "CHRD" header, and seem to be compressed with various formats. Any help on how to decompress these?
Here's a Example file (and incidentally the one I'm most interested in as it's the biggest file inside the AFS archive):
https://www.dropbox.com/s/x7yn6bfb6yukr ... p.pak?dl=0

Anyone got any ideas on this?

So I did some experimentation, apparently the file in my link is looking like a LZ77 compressed (Or a specific version of LZ77, either way) file, so that's looking like a good start, at least.
I wouldn't be surprised if it's not a common form of LZ77. Most PS1/PS2 ports of game don't really have a standard compression format.