The Final Solution is a mod for registered Wolfenstein, made by Parafriction.
Version 3.0 was released on August 19, 2001. It was preceded by Version 2.0 which had originally come out in December 2000.
Version 3.0 added landmines, ambient sounds, and added a breakable object (a steel cage). Furthermore, many enemies and standard sprites were replaced or souped up using those of version 2.0. A number of new textures unique to the mod were also added.
Some levels were edited containing new sections or redone altogether. Level 4 was brand new, not having appeared in version 2.0.
When released in August 2001, Version 3.0 was labeled as a beta in the description and as a demo on the title screen. An actual, final full version has thus never been released.
Source code
The source code was released on June 23, 2002. Not long after, mods started to appear using the source, including ToMeanToDie's Kristallnacht and Great Wasabi's Dead World Rising.