Project Totengräber is a mod for registered Wolfenstein, made by BJ Rowan. Initially released as Phase I on October 30, 1999, Phase II came out on December 24, 2000. This sometimes went by the moniker Totengraeber II.
The first phase included 27 levels; 24 regular and 3 secret levels. Phase II expanded the original version with 21 levels, making the full total 48 levels; 41 regular and 7 secret levels.
The mod was the first large-scale mod in the Wolfenstein 3D modding community, in that it featured a host of changes (seamless levels, a variety of secret levels, including super secret levels, ammo box from Spear of Destiny, tons of new graphics and sounds, mainly originating in the MAC version of Wolfenstein 3D) and furthermore introduced one of the advantages of seamless level flow; slotting the storyline into different parts, each with a different theme. The player is taken through a host of different castles before ending up in a laboratory area, each unit connected by a slimy tunnel, not too different from how Spear of Destiny was constructed.
The story is described in an included text file as such:
It is 1942, at the height of the Second World War, and the Allies are fighting a fierce battle against the Axis Powers in Europe, and the conflict looks far from over. Worse, the Allies have reason to believe that the Nazis may be amassing a new army of undead soldiers to do battle for them. It is rumored that a top Nazi scientist, one Arzt Schabbs (generally considered mad by his former colleagues) has found a way to resurrect soldiers who have been killed in battle, graft a third arm onto their chests, and send them back to the front lines - in a macabre experiment known as "Project Totengraeber" (effectively, "Gravedigger"). Some such undead soldiers may even receive special conditioning to carry out suicide missions no sane man would ever accept. With no concern for their own lives, only a bitter, ingrained desire to kill, Schabbs' zombies would have nothing to lose in a firefight, attacking relentlessly and with unimaginable determination. This appalling possibility leaves some in the Allied military aghast, some disbelieving, and all horrified. But the prospect seems very real, and if it does turn out to be true, this new army of undead warriors could spell doom for the Allies - as it effectively means the Nazis would have an unlimited supply of soldiers for battle. Death on the battlefield no longer spells the end for those subjected to Schabb's lurid experiments. And unless Schabbs and his army are eliminated, the war could begin to take a terrible turn for the worse for the Allies - and indeed, for humanity itself.
There are other rumors afoot as well amongst Allied Intelligence officers. Recon teams coming back from top-secret missions deep within enemy territory have reported a suspicious amassing of soldiers and top Nazi generals in a localized area of Nazi Germany. This mountainous region, home to several ancient German castles, was originally thought to hold no strategic importance, but apparently the Nazis have some sort of secret operation underway in that sector. Could it be related to the rumored Totengraeber project? Could the execution of a massive new Nazi campaign be imminent?
Desperately seeking a means to combat this potentiality, Allied Intelligence has brought to the table several recently-acquired maps showing the locations of six German castles in this questionable region of Nazi territory, each of which is suspected to play a key role in the mysterious Totengraeber project. The Allies believe that a concise plan of systematic elimination of these key Nazi installations, including Arzt Schabbs and his undead army, is an immediate necessity. According to Intelligence, the six castles are interconnected via a system of old tunnels, which can also serve as bomb shelters - and, depending on their magnitude, possibly one or more secret bunkers or laboratories. The tunnels were constructed around the time of the first World War, and now the Nazis are apparently using them as a secret transportation route between their key bases of operations. They are, however, relatively lightly guarded at one particular position. Considering this position a perfect "back door" by which a one-man strike force might gain access to the castles and destroy Project Totengraeber from the inside out, the Allies decide to recruit their most effective one-man strike force for the job - a man by the name of Captain William J. Blazkowicz, or "B.J." to his friends.
You are B.J. Blazkowicz, and your commanding officers are sending you deep into the heart of Nazi Germany to stop Project Totengraeber if it exists. Castle Sturmwind, an ancient Prussian castle in the southwest area of the target region, is lightly guarded and has been designated as your entry point. You will enter the castle's ground level, and work your way down through the cellars to the tunnel system beneath. From there, follow the tunnels as they wind northeastward. The tunnels apparently connect with the lower levels of several other castles, and you will most likely find it necessary to work your way through those floors and back into the tunnels at some other location. Allied Intelligence believes the tunnels will eventually end up beneath Castle Dolchteufel, where it is believed the entire Totengraeber project is being spearheaded. Along the way you may find yourself caught up in head-to-head firefights with the high-ranking Nazi generals who are in the area, evidently overseeing the final stages of the project's execution. Your orders are to eliminate as much Nazi resistance as you see fit, but remember that your primary objective is the assassination of Arzt Schabbs and his legion of mutated walking dead. Schabbs may be holed up in a secret lab in Castle Dolchteufel, at the center of the secret tunnel system. You must take him and his army out at all costs. This is your toughest assignment yet, and you will be up against some of Hitler's finest. There's lots of ground to cover out there, so fight hard, keep your wits about you, and remember to make use of the Nazis' health and munitions to keep you going. The Allies are counting on you, B.J. Go win one for humanity...and try to come back alive!