So there was a computer game in the 1990s that scared me as a kid, not sure if anyone else here played it:
The game involved you, the protagonist, stepping into a labyrinth-type maze. At the very beginning, there is a dead Nazi officer lying on the ground. You go up to him and pick up his pistol and ammunition. Soon thereafter, various alien-type creatures with tentacles coming out of the heads starting pursuing you through the maze and you need to shoot them while trying to find some way out. The game’s colors are in something like night vision - everything dark or green.
I looked up Wolfenstein on YouTube (hadn’t heard of its 1990s version) and…it doesn’t fit. No aliens. There were no other humans in the game other than you, the protagonist, and the dead Nazi on the floor.
In one module of Wolfenstein 3D, Operation: Eisenfaust, the main enemies are mutants created by the Nazis as an undead army. I don’t remember if they had tentacles coming out of their head, but what you describe matches everything else.
That game was a prequel to Wolfenstein and was basically the same game, just with different bosses and slightly tweaked storyline. It doesn’t fit the OP’s description.
Meanwhile, here is a screenshot from the previously-mentioned Pathways into Darkness.
Note, very dark and green visual, alien-type creature with tentacles coming out of the head. The game’s plot also includes “fallen members of a Nazi expedition from the 1930s who were looking for a secret weapon” per Wikipedia. Also, here is a “let’s play” article about the game:
The game does start with you entering the dungeon and almost right away finding a dead Nazi that you loot a pistol and ammo from. (You start with a pistol but no ammo, and the Nazi has ammo for your pistol, and also another pistol with its own ammo.)
That’s the dead Nazi on the left in grey uniform.
I can’t imagine that this can be any other game.
Maybe @Velocity can return and confirm if this is correct.
Thanks Atamasama and Pork Rind. It may be. I was only 7-9 years old at the time so I may be misremembering some important details. And I had only seen the game once - was watching while someone else played. But thanks for the sleuthing!