Ok, I've been trying to find this wad through magazine CDs from back in the era for almost an hour. Worst part is that many filenames seem familiar to me because I probably played them, so it's a huge setback.
1. I am talking about a single level for Doom 1
2. Really old shit, probably from mid 1994
3. I remember been blown away because the level itself was the biggest single level I had seen so far, with a size around ~350kb
4. Replaced E1M1
5. On top of that, the wad also featured super random monster replacements from the era: Imps were Pacman, Demons were Barney the dinosaur
6. Of course you had to merge those sprites with your iwad with deusf for it to work
7. (my memories about this point could be misleading) I recall kind of a spiral staircase near the beginning
8. (also not sure) Since it had all kinds of lame replacements, MAYBE Doomguy had the sunglasses mod in the hud.
9. You couldn't save game... because Thing limits were hit in that level