Modding Wolfenstein 3D or DooM.
 

Hay.

I want to make a clone of Wolf 3D or DooM, whichever is easiest. Where do I start?

cYa.

From a Freeware Community?
http://www.reloaded.org/

Source code for Wolfenstein 3D was released way back in 1995, and for Doom in 1997.

As to where do you start:
http://en.wikipedia.org/wiki/Wolfenstein_3D
http://en.wikipedia.org/wiki/Doom_%28video_game%29
There are some links to modding communities for both games there. Go ahead and check them.

Hmm, I don't know how I overlooked those links. Thanx0rz for pointing them out. :}

got 3 links that might interest you:

NewWolf - Wolf3D for openGl *best mod out there*
http://newwolf.sourceforge.net/

wolfendoom
http://www.doomworld.com/wolfendoom/index2.html

wolftc (in progress)
http://forums.newdoom.com/showthread.php?t=28402

Modding
 

I have made a mod myself to, i dont know the name of the modding program i used (was around 1 year ago... a friend sended the file) i made a rocketlauncher, an auto-target launcher (aim over the enemy for 2 secs, and the rocket locks on... VERY handy with the last boss i made... cuz he runs around like crazy :P)

It's too bad doom tc project just will never see the light of day. WolfenDoom would have been better if it was ported to the Duke3D engine :)

If you are interested by Doom, you may want to check the Doomsday HQ, for their Doomsday engine.

As the engine has been heavily modified to be able to support modern effects, models formats etc.. it may be more open to modding than originally.

Start DooM modding by making WADs. Try Doom Builder. Works nice, and has a 3d mode.

@D4NG3R: Is it DeHackEd?

ooo that might just be possible :D, but im not sure tho... i think i used that program to (to make the last boss for my home made episode; Return to the heir, you return to hitlers base to discover that the origional one you killed was just a clone), but i cant find the file for it anymore (new pc eh) so im looking on my older pcs to find it