Rough around the edges, but deeply endearing. It brings to mind my own early level design attempts—loose ideas dreamed up in class, excitedly transcribed directly into brushwork, focusing on the fictional role or the mood of the space over its gameplay, without so much as a blockout phase. I don't know if that was the author's process, but that's the vibe I get. The occasionally fiddly geometry and weirdly specific detail flourishes speak volumes.
Their imagination and passion shines through, though—there are lots of memorable spaces and fights that make the experience a joy, even if the encounter design clearly needs work. The long foreboding corridor to the Shambler's shadowy home, or the fight on the narrow catwalks high above the warehouse floor, or the battle with a horde of Grunts/Enforcers under the dome of some kind of moon base. They all have problems with their implementation, but they all contribute something fresh and different to the experience. I've played many more competent maps that stuck in my head less than this one did.
Very cool. Excited to see more from this author.