I know it's a hidden achievement, and I haven't done all other hardcore level achievements, and I am unable to check with anyone else who has this achievement as it appears they unlocked every achievement at the same time (which seems strange :) ). If there is any hint or way that I can do this, please let me know!...

The store page mentions that the music was done by RWG, do you know if they have a profile at any of the music sites out there where one could find more of their content? Sometimes you just want to put a little background music on while doing other things and both the trailer tracks seem like they'd be something i'd love to have playing while engaged in other projects....