I don't know how I managed to push this off for so long, but I finally beat Quake 1 yesterday! In retrospect, I think it's super impressive that as a kid I tried to play through Quake via Quake 64 via emulator... one that ran in a browser window with 320p max resolution. That was like 10+ years ago and I got as far as Q64's version of episode 4. Within that time, I'd try to beat Quake but always quit around episode 2.
Personally, I was always more into Quake 2 with its power fantasy gameplay as opposed to the lite-survival horror vibe of Quake mixed in with difficulty spikes of id's older shooters. I saw news of the Nightdive remaster and took a week or two to wreak havoc once more on Stroggos. Finishing Quake 2 recently really pushed towards the realization that I should force myself to beat the original!
What really got me back into Q1 though was a Noah Caldwell Gervais' video essay tackling the franchise from a narrative/story perspective. Playing through Quake I kept in mind Noah's observation that each episode is sort of accomplished through auteur style design of the levels. Despite being the most difficult, I really enjoyed Sandy Peterson's levels. E4 feels abstract, but not in the way that Doom was. They all unfold in a way that reflects the game's cosmic horror vibe.
It's wild to see the direction the level designers went in after Quake, since time constraints forced them to settle on Doom 3 but in 3D but it's not doom, but there are traces of that original vision littered throughout the game. I'm sure folks here have played 1000x more Q1 than I have, so it'd be cool to hear any opinions on the meta and design of Q1.