Return to Wolfenstein is a Registered Wolfenstein 3D mod by Kurt Fankhauser released on New Year's day 2000.
The story is described in an included text file as such:
You are called to the Pentagon by the secretary of deffence and notified of some suspiciouse Nazi activity possibly a plan attack againsted the United States. Rumer has it that schabbs has been revived and is now training a highly destructive army. A bigger more powerfull Nazi army is what everyone has feared. But who is he training and when will they attack. You are warned again that this mission is very dangerouse. As you fear for the United States you accept the mission and plan to leave immediatly.