Description:

Yadex is a Doom level (wad) editor for Unix systems running X,
including Linux. It supports Doom alpha, Doom beta, Doom, Ultimate
Doom, Final Doom, Doom II, Heretic and also, in a more or less limited
way, Hexen and Strife.

Yadex is descended from DEU 5.21. Therefore, as you might expect, it's
a rather low-level editor that requires you to take care of a lot of
detail but on the flip side allows you to control very precisely what
you are doing. In addition, it has many advanced functions that DEU
didn't have, to make certain tedious tasks easy.