Gotterdammerung is a mod for registered Wolfenstein, made by Raistlin. It was released on July 30, 2003.
It features a number of coding changes, including textured floors and ceilings, increased health and ammo and many new textures and graphics, many with a dark gray sheen.
8 levels were featured, all of small size. For the rest of 2003 and 2004, Raistlin would sometimes make a post on the DieHard Wolfers' forums about getting back and finishing the mod properly, but this never came to be.
For its time, the strength of the coding pulls up what is otherwise a slightly wasted effort. It is nevertheless still an extensive, though brief, gameplay.