reversing the doom levels?

Is there an easy way to reverse the doom levels? like just flip them in an editor some how? I've looked in gzdoombuilder and didnt see anything, I'm trying to reverse all the doom 1 and 2 vanilla levels. Any help is appreciated thanks!

If you just want to play them that way, you could try using Crispy Doom with the -fliplevels switch. It's pretty fun.

http://www.chocolate-doom.org/wiki/index.php/Crispy_Doom

I want to do it for a mod im working on, so it will replace the original levels

Aw come on! I am just making a mod in which you play Doom in reverse order from E4M8 to E1M1... I just lovei t.

wow thats cool I like it! I just want them in normal order but is there any easy way or does it all have to be done manually?

whats the name of your mod?"

Select the entire map, hit E to enter Edit Selection Mode, there will appear options/buttons for Horizonzal and Vertical Flip on the panel with editing icons, press one and the selection will be flipped. It can easily mess up many alignment-sensitive lines/textures, though.

Also, obligatory mention of the fact that distributing modified levels from the commercial IWADs is not legal, unfortunately for your mod idea.

Oh well im using all new textures so if i reverse the levels its still a copy write issue? damn,I guess that means ill be making my own levels then.

Try this tool https://www.doomworld.com/idgames/utils/wad_tools/mood_v12
Imo no need to worry about copyright that much, it's only for nerds.

Or in normal terms, it's only for those who wish to upload it to /idgames which I wouldn't worry about until you're confident in your mapping/modding skill.

WARM (the nodebuilder) can do that.
warm -flip in.wad out.wad
If you only give one filename, it overwrites it...
It can also randomize thing placement, but that's only useful for deathmatch, unless you edit the code so it leaves keys alone (it's a small, easy change).