The New Breed is something I worked on all by myself for about a year and a half. I started with learning maps, ended up making some killer DM maps, then I found DeHackEd. With it, I hacked my way deeper into DOOM's EXE more than any other, even Aliens TC.
Lighting in the maps are pretty realistic, and for the time some of the first maps to use the multiple sectors to simulate faded lighting. You'd think you were in Quake. :)
I also added new sprites, environment sounds for water drips, waterfalls, streams (along with animated floor textures and wall textures for moving water), lightning, wind, computer noises, errie squeeks and noises, and others. They really set a mood like no other TC has.
The highlight of The New Breed is the weapons. You want power? You got it.
-chaingun (base weapon -no more pistols)
The good news is it works with Legacy and other source ports. So you can have MLOOK, jumping, fire up and down, high resolutions! It rocks!
-two part Apache chaingun set (side mounted war helicopter chainguns, awesome power and speed in firing)
-flame thrower (this is the most powerful weapon, and also most hazardous to yourself!)
-faster rockets from the rocket launcher (they also emit smoke as they fly by, and explode in spectacular flames)
-napalm gun (gotta see this to believe it!)