Mr. Chris's E2 series
Stoned An E2M1 clone, more or less. Actually rather good. Looks decent but not too showy, uses light and dark well, and is not too hard (although there was one trap that seemed noticably nastier, but it caught me off-guard - I got past easily when I was expecting it)
Iconic This is a trek through a base, loosely based on E2M2 although I can't see it much. Was all right, fun enough, but somehow not as good as the previous one. Can't really say why. The "corridor of traps" was pretty entertaining. Charge and let out everything at once, it's more fun that way!
Abyssus The author put a lot more time into this one, it is significantly larger and more well-made. This is a really nice level. Author makes good use of light and dark contrast again, although somehow I feel it needs more sourced lighting. Difficulty is pitched just right for me, except for being a bit short of ammunition occasionally (but I survived, somehow)
Some traps need tightening up - if you lock the player in a room, do it before you open the walls and let the monsters out, and put the monsters where the player can't hide from them without waking them up until the door opens again - and I thought there was a bit too much backtracking, like you get the blue key and have to run all the way across an empty level and almost back to where you started from. Lots of secrets, most were fairly easy to find if you press on absolutely everything and keep your ears open.
Author obviously used a GL port to test as there are floating middle textures sunk halfway into the floor, but oh well. It only ruins the look of one place in the map.