Yadex is a Doom level (WAD) editor for Unix systems running X.  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.

WWW: http://www.teaser.fr/~amajorel/yadex/