...while Wolfenstein was in turn one step forward and two steps back from Castle Wolfenstein, circa 1984.

The step forward: moving from top-down map view to 3D first person shooter made the game feel much more immediate. Besides, at that time 3D, any kind of 3D, was just cool.

The steps back: in Castle Wolfenstein you needed a lot more stealth and cunning. For instance, if you found a german uniform and put it on you could fool most regular soldiers and just walk right by them (don't get too close though!). With the addition of some war medals you might even be able to fool the dreaded SS (again, don't get too close or act strange). Once you got the SS on your tail it was almost impossible to lose them, they just didn't give up. You could usually outrun them, but they would always catch up. Killing was the real way to make your self safe. However the more bodies you left lying around, the less likely your pilfered uniform (and inability to speak german) was likely to fool anybody.

And finally, you weren't just trying to escape Castle Wolfenstein, you were attempting to assinate Hitler and his top officials. This required:

1. getting a uniform,
   
2. getting medals,
   
3. acquiring an SS uniform,
   
4. pilfering some SS medals,
   
5. some other stuff I don't remember,
   
6. filling a briefcase full of explosives (which you had to find first),
   
7. attending the meeting of the top brass,
   
8. arming the briefcase bomb
   
9. hightailing it out of the castle before all hell broke loose.