Level 80 is a mod for Spear of Destiny, made by Poet. Initially advertised but unavailable for download on his website, it was later made available. The exact date is not certain, but files date to October 2012, the same time Poet was egged on by Thomas Weiling as not ever having publicly released the mod.
The one level was actually an outtake for Poet's contribution to the John Bucksnort tribute set which had come out in 2002, and the atmosphere is definitely felt. The level design is a spectrum, vaguely reminiscent of the Ramparts level from Spear of Destiny.