Can be easily opened with https://github.com/wmltogether/CriPakTools
Contains the usual dat and dtt and so forth just like some of their other games though some things might be updated.
I was able to extract textures but some are somewhat "corrupted"(or are just aux data like directional lightmaps)

Sample file: https://transfer.sh/13foZS/um2140.dat
There's some other file formats contained that could be mapped out. Some of the CPKs contain a lot of wd_ files(world data. Much of it procedurally generated using Simplygon with not much else going on.
data012.cpk contains a lot of quest and scripting data and the licenses involve a lot of ruby so there might be a huge repo of ruby scripts somewhere among the assets.
the .z files found within the .dat files are predictably zlib. An example of a decompressed "q171_hap.z" file found within "q171.dat" which is within "data012.cpk"(so many nested levels of files...)
http://pastebin.com/raw/0rJZ4CKH
pak files are pretty much containers for multiple zip streams.
Found all around the archives are what looks like "compiled" ruby code. Constants and some signs of syntax are exposed here and there. Probably pre-lexicographed ruby code to avoid storing pure plaintext.

Very likely it's just pre-compiled mruby VM bytecode output from mrbc.
https://raw.githubusercontent.com/mruby ... y/opcode.h
Bin files found in quest data such as 'q171_12f2963a_scp.bin' is for sure output from mrbc. (the ones with the `RITE0003` header)
https://github.com/mruby/mruby/blob/08a ... dump.h#L53
Some of the middleware that Nier uses:
https://github.com/mruby/mruby
https://github.com/antimon2/enumerable_ ... /README.md
https://www.musl-libc.org/
http://rake.rubyforge.org/
https://github.com/yhara/enumerable-lazy
https://www.simplygon.com/
http://www.geomerics.com/enlighten/
Made a quick extractor for the .dat file files.
https://gist.github.com/Wunkolo/213aa61 ... ebb8ab89c2