I dreamt I was the player in a first person shooter that had to have been set in goldsource. It was horror-esque and I didn't have the best weapons (shotgun, an smg, a bolt-loaded rifle - the enemies were long-ranged and the rifle was only effective against enemies with a head). The low texture walls and the low-polygon enemies whose textures were just flesh and eyeballs and such made this whole thing super uncanny. Some of the enemies were humanoid-like with gigantic toothy mouths that spat projectiles at you, another was a giant fleshy-hand with eyeballs and a large gaping mouth in the center of the palm that was tanky because it didn't have a head hitbox. The map had secrets like a Doom game and I tried going for all of them on this level but woke up when I found an optional boss.
Some of the enemy designs were like enemies from Ziggurat and the optional boss looked kind of like a gonarch from HL1. I probably didn't explain it very well because I just woke up but man the oldschool aesthetic can be kinda impactful (see: Xen. It's textures don't work well on newer engines).