WTC 911 (no, not what you're thinking, it stands for Waste Treatment Center #911...) is an Episode 1-style Doom level, and as you might guess it is set in a dark, "factory" type environment.  It actually captures the feel of the Episode 1 levels very well (particularly the more spookier ones).  But here's the interesting thing: it's not exactly imitative of them either, because there are no areas or situations that are "recreations" of any of the Knee-Deep in the Dead originals.  And in fact some non-Episode 1 textures are liberally used too.

The level is not a very big one and so navigating should not get confusing.  You basically start off by taking an elevator to a sort of balcony/corridor overlooking the place where the waste is actually being treated.  You then follow the path from here and go through some corridors.  Eventually you get the yellow key and go back to the beginning of the level.  Behind the yellow key door, you will soon get the blue key and then it's off to the exit.

The level provides a nice challenge on Ultraviolence skill without becoming overly difficult.  As long as you don't rush into rooms and waste ammo you'll be fine.  The monsters used are the Episode 1 monsters only, and while there are not too many of them, they are used very well.  I particularly like this about WTC 911, because at no point does the monster placement compromise the generally spooky and dark feel of the level.  The author also doesn't miss the opportunity to throw in a surprise.  There is one secret in the level which does contain a useful item, but unless you know beforehand where it is, it is probably of no use at all while normally playing (you'll know what I mean when you find it).

Texturing and lighting are also done very nicely.  A couple of new textures and flats are put in, but they fit in very well and you won't even notice them unless you're told.  The lighting style is something unique - you get to see lights cast in some nice shapes and some cool glimmering effects (especially in the exit room).  The detail level is also similar to the original Doom 1 levels, and the whole thing looks good (though I felt that the main waste treatment area was a bit low on detail).  My favourite part in this level is the one in the second screenshot, for some reason I love the atmosphere of that room.  The level uses the music from E1M5 to enhance the atmosphere and it works wonderfully.

There are a couple of issues here though.  First of all, there are two WADs that you will have to load to play the level properly (wtc911.wad and wtcgfx.wad).  I think it would have been better if they had been merged into one (takes only a few seconds to do that).  Also, when I played this with the normal doom.exe (the Ultimate Doom 1.9 one), it crashed at one point with a "No more visplanes" error.  This happened after I pressed the switch to open the door to the room with the yellow key - when I looked at the "shiny steel" area with this door open.  Anyway that's easily solved by playing this level with an enhanced engine as most people do.

A nicely built level, this - it should be of particular interest to Phobos-style level fans.  I also think it is a pretty good level to record demos on.

The author mentions that this level might become the first in a set (that probably explains the position of the secret area) and I would certainly enjoy more maps like this.