OK. So as the subject suggests, this is a 4 level Zdoom mapset. The levels are huge, and very detailed, but they play pretty well.
Screenies...
http://profile.imageshack.us/user/kysev/images/detail/#61/map04tm8.png
http://profile.imageshack.us/user/kysev/images/detail/#115/map04aek8.png
http://profile.imageshack.us/user/kysev/images/detail/#139/monstermus2pngjn7.png
http://profile.imageshack.us/user/kysev/images/detail/#398/officepngxc7.png
Link: http://www.speedyshare.com/419831990.html
Note: This has been up on Doomworld for the last week or so. If you already got it there, these are pretty much the same maps (with some modifications).
Thanks (again) to Jodwin, Dreadopp, KingKill33, Jimi91, gggmork and Creaphis for playtesting, as well as loads of feedback.
Last thing. Make sure you play these maps with the music ON. The music is by Jimi91 (Maps 1,2 and 4) and stewboy (Map 3) and it is awesome.
Any feedback, criticisms, thoughts etc appreciated.
Other maps in progress for this project:
Map 5 (50%)
Map 7 (80%)
Map 15 (20%)
Map 17 (finished)
Thanks people.