Unholy Realms is a
limit-removing megawad by
Brian Knox with four guest mapper contributions and full original soundtrack by
John Weekley. It's the last Doom project Brian was involved with, and exhibits a remarkable flexibility in his approach to level design.
Footnote: MAP23 is not possible to UV-Max as it contains Boom triggers, switch compatibility with TNTCOMP cheat or else, up to your discretion.