Operation Wasserstein was a mod for registered Wolfenstein, made by Lance.
The mod was in the pipeline during 1999, before the days of the Wolfenstein 3D Dome news. This makes any history of the mod hard to decipher. Lance's website still functions as an archive item, and the known information on the mod is as follows:
Multiple versions were made (v1.1-v1.3) and the mod was definitely available for a time in some form or other.
Coding features included four keys, changed ceiling colors, adding a heartbeat sound as BJ's health lowered, and guards had higher hit points, making for quite a tough playback.
The beta testers may have accidentally leaked the mod or made it available, as Andy Nonymous remembers playing it. In either case, the mod never made its way to the Wolfenstein 3D Dome, and by the time various forums appeared it had been all but forgotten.