Nonlinear wads/mods

Are there any wads were there are branching path ways like exit A leads to path A having different levels exit B leads to path B and so on and if there isn't does this idea sound interesting to you?

I want to say that someone here did this very thing a year or two ago. I couldn't tell you who or what it was called, though.

Alwaysdoomed tried this out in Global Death

It's also a feature of Temple of the Lizard Men 4

Urania, if you have enough time :)

Darkmoon by DMPhobos and Z0k fits the bill and is a fun experience; I hope they finish it some time :)

Miasma is a very nice nonlinear single map.

The Tei-Tenga Incident have maps interconected .

UAC Rebellion offers different paths depending on which exit a player chooses (or finds first) on certain maps. Depending on which paths you take throughout, you can get to the end having played anywhere between 8 and 15 maps.