Thank you for your feedback, tcassat.
I wanted the levels to be progressively more complex. In the first one I wanted to experiment with narrow spaces and long hallways, which is something you don't normally see in the original game.
I may consider changing the secret silver key access passage to a normal lever-door access. I don't know why I put that in there. I guess I was improvising.

I finished the campaign without saving, on the highest difficulty with all the "vanilla" game mechanics. I liked the levels, I think I did them all (I don't know if there are any secret ones).

I personally liked the later levels better (from the third level onwards). The first one is the only one I found a bit "meh", there's a maze-like design to it that I'm not a big fan of, and progress depends on noticing a secret passage, but it's not that hard to find.

I haven't checked it out, but I think it's possible to skip that whole night city level by jumping over the fence at the end with a rocket jump or with the dog (bark + use). I wanted to check it out, but I still haven't figured out how to select levels in this damn game so I'm not sure if it's possible.

But all in all, good job.

Feedback is always welcome!