I just had to post... Love this level, but things like this often go under the radar. It's a Hexen inspired castle, with a variety of monsters from KDIZD, Doom 2 and many brand new. It has moody lighting and intricate detail throughout. Highlights include the hoard of new monsters, an unreal-esque mirrored floor, an interactive, macabre dungeon, and interesting finale.
Gameplay is v.good and the secrets (unmarked) rewarding. You should probably make sure to get the plasma gun amongst the towering stacks
of the library as it's sure as hell not easy. (I cheated a couple of times).
Game was played on skill 2 (out of 5) with GZDoom v1.1.4 (GZDoom 1.1.0 or
newer recommended).
http://www.doomworld.com/idgames/?id=15522