At some point we considered making bullets leave holes in the nazi flag sprite.
The idea was dismissed by the team for making hard on the player to shoot nazis through it (especially as we already have such a lamp) - and also the holes on the flag might look too big for bullets.
What started as a "Rust (locked) Door" became a "Horror door" later during the project.
You can still see the remains of the "rust" in the brown color of the "Horror key" (originally the "Rust Key") - and it the normal Rust Doors. At first those were all brown-colored - but later I came out with it's current look, that makes the rust more recognizable and realistic - merging it with normal metallic color.
I did put alot of creative thought before inventing the "Horror Door" art concept.
We used different dark/light variants for many walls - to increase unique look, wall selection and realism.
Not to mention the use of Wall Patches - that though were added relatively late - helped alot to create endless wall variants. If we'd use Wall Patches from the beginning of the project - we could save alot of walls spots in the VSWAP.
As you could probably notice - we've left quite a few sprites from the original Wolf3D as a tribute (and also too keep Wolf3D feel) - mostly skeletons and gibs, hanging skeleton etc. (2 other gib ideas came from "Blake Stone".) But also the ammo clip, barrels with little editing - and such stuff. Brown barrels are just recolored (an animated) green Wolf3D barrel. This means recolored back to Wolf3D green it can help many future "more classic" Wolf3D mods to make the barrels more interactive. Barrel animations were made by me from scratch, and I'm quite pleased with the outcome.
In earlier versions of the Eisen EXE, way back in its 16-bit days, there was a *very* interesting bug related to mines. Originally, the mines you ran over just took away 20 health, and didn't check your health status afterwards (You could even walk past them safely if you maneuvered through them at the right angle). So it was actually possible to wander around with -19% Health for a good deal of the game. When BJ's health was far enough in the negatives, the animation on his face was extremely strange, going from the Chaingun Smile image, to the BJ Killed image, to BJ's "Razz" image. Really weird stuff.
Also, as Tricob adds, the mines that appeared in the game were originally a pile of tacks. Among other problems, the tacks were very, very hard to see in the green grass, and that's exactly where they were placed most of the time.
In early versions of Eisen:
1. Rifle dude had normal standing shooting frames
2. Black officer was the basic guard
3. WSJ officer was replacing fast black officer
Near the release some art was improved by me - including the MP40 frames, and forest bottom part to be more consistent with normal grass/snow floor textures.