Insane 5-D was (and is) a Wolfenstein 3D project, courtesy of Nexion. It was announced in February 2008 and was mentioned as having a dark, trashy and morbid atmosphere.
A few test shots were posted, and though no news have been heard on the project for a while it is not off the table.
When pressed for comment, Nexion stated:
"Insane 5-D is indeed still in the works. Looking and playing sweeter than ever, I expect to release it in ∞"