My entry for CutmanMike's second Doom Mutator Contest, in which contestants create a new gameplay mod using no new sprites, sounds, or maps - code only. So using ZDoom's textures system and some clever Decorate tricks, I cooked up this thing.
Xaser who inspired me, #zdoom on Espernet for bug tracking and ideas.
New from scratch
SLADE 3 Beta 5
If ZDoom crashes on startup with an error about SMF_PRECISE, go download the latest SVN build from http://svn.drdteam.org/