How to extract an unknown archive files? (umd “I am alive” PC)

Question

I'm trying to extract game files which contains textures, meshes etc. I wanted to see how hard would it be to make a texture mod. I just have knowledge on editing graphics from school and youtube tutorials and I'm really lazy and give up on something really fast but I thought if I could work on this game from the very beginning, having a whole structure of files which I could make sense of (not like with ninjaripper) maybe I could motivate myself to do this. I tried to use quickbms script and some tools from xentax and zenhax forums but quickbms gave me and error and the tool did nothing. I'm a total beginner to reverse engineering as I've only touched it because I didn't have much to do.
I've got the header of the file which is EPCK, then the next line I guess is unpacked file size (based on offzip scan seeing almost all files with size of 131072) I have the offset refering to first file in the archive? which is 29, and I have a part which is the beginning of each file? which is ".x" or "x". I've tried to understand quickbms script to see if I could make something of it and what was the reason that I got an error but even though I understood that it makes array which stores the offset I couldn't understand the reason behind the error. So long story short I need help with next steps to unpacking the file. I'd like to understand it completely from the beginning so I could help other beginners or so I could just stop asking for help. I guess it'll be really hard to understand for me since this archive is probably encrypted. Quickbms script gives an error on line 42.
Script: https://mega.nz/#!BpNFAKaB
File: https://mega.nz/#!tlMzUSiT