For Doom 2 with Legacy
Or you can add sprites to the wad and patch your normal doom2.exe
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Title                   : Doom From Above or Airraid Doom pre-beta
Filename                : airraid.wad airraid.deh
Authors                 : Gokuma
                          Eidolon (anti-aircraft machine gun turrets)

Description             : Unfinished pre-beta.
                          You fight off airraids.  When damaged by missiles
                          anti-aircraft defenses shoot back at the aircrafts.
                          Watch out.  A bunch of bombs drop from the sky at
                          the beginning of each level.  On the exit pillar
                          the switch facing the wall restarts the level.
                          In the first level you have nothing to attack
                          the aircrafts back with.  You are dependent on
                          the gun turrets and SAM sites.  In the second level
                          you have weapons but more aircrafts to deal with.
                          The BFG explosion has been changed for the time
                          being.  The third level is exactly the same as the
                          second except the missiles are set at all different
                          heights when they drop at the beginning of the
                          level so they hit the ground at different times.

Plans:                  : See copyrights/permissions.
                          This patch has a good idea behind it and has the
                          potential to kick ass if worked on more.
                          The machine gun terets suck and accidently shoot
                          each a lot.  They should either be taken out of
                          this patch or they should be isolated on pillars or
                          something and have the gfx replaced with better
                          ones.  The SAM site gfx suck and should be
                          replaced.  It would be cool to make an airport
                          level.  I think the bombs dropping at the beginning
                          of each level is a cool effect.

Additional Credits to   : Id, 3D realms

Usage                   : doom3 -file airraid.wad airraid.deh

Heh, it's funny how I typed so damn much about such a small unfinished patch.
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* Play Information *

Episode and Level #     : MAP01-03 although they're just modified versions of
                          the same level.
Single Player           : Yes
Cooperative 2-4 Player  : Yes
Deathmatch 2-4 Player   : Yes
Difficulty Settings     : I'm don't remember if implemented
New Sounds              : Yes
New Graphics            : Yes
New Music               : No
Demos Replaced          : None

* Construction *

Base                    : New level from scratch
Editor(s) used          : A bunch
Known Bugs              : none


* Copyright / Permissions *

Authors are incouraged to use this patch as a base to build additional
levels as long as credit is given.

You MAY distribute this WAD, provided you include this file, with
no modifications.  You may distribute this file in any electronic
format (BBS, Diskette, CD, etc) as long as you include this file 
intact.

* Where to get this WAD *

http://gokuma.neocities.org