This pack has been mentioned in public contexts on multiple occasions, including the above videos, but had never been released to the public due to concerns regarding fragility if not installed/run properly and concerns related to the modifications made to several mods. See "Warnings" for more details.
The pack is released with three difficulty levels, to allow choice in what kind of experience users of the pack wish to create. "Hard" is the official version as of this writing and is strongly recommended, as it is both closest to the experience intended by Reika and the only one that receives regular updates.