I remember renting Doom 64 and being super surprised the first time I started the game. Even if my only real extended experience playing Doom myself was on my SNES, I obviously could tell straight away it was a totally new game, which was a bit of a shock.
The game got kinda short shrift by the world in general; even if looking back it's obviously a super high quality original project, a lot of people focused on the missing multiplayer and the fact that... Doom was "old fashioned" at that point, especially when fancy full 3D games like Turok had just come out weeks earlier and GoldenEye was six months away.
Replaying it years later was super interesting. Beyond the extreme darkness and Aubrey Hodges soundtrack, it's got unique flavor. The levels tend to be more switch and navigation puzzle based (almost to the extent of something like the Memento Mori megaWADs), which can be a bit much, but it also has its own twists on famous staples like Dead Simple and some bonus maps that are in a similar vein to Doom II's more gimmick-oriented maps. Playing it in the dark can be almost disorienting and anxiety-inducing, and the tone of the interstitial texts is way darker. Doom/II/Final Doom interstitial text tended to be a bit more playful and comedic, playing off the Doomguy as this increasingly tired-of-this-shit sap who just couldn't catch a break until he kicked everyone's asses. Doom 64 depicts the Doomguy as slowly going insane due to the stress of doing this over and over again.
For comparison, Plutonia Experiment ends with a gag about how you should tell your grandkids to put a rocket launcher in your coffin so you can keep killing demons after you die. Doom 64 ends with blood pouring from Doomguy's eyes as he resolves to remain in Hell for all eternity to make sure no demons ever return
