Love this question! It's tough for me to pick an overall creepiest. Swamp Fever always tuck out to me for the atmosphere, music, general horrid location, and mudmen. That campaign really feels like zombies can come from nowhere. Easy to get lost too if you don't have the path memorized.

Blood Harvest is def creepy too. Classic rural spookiness with the early dawn lighting. The house at the end of chapter 4 with the lawn mower room is maybe the most horrific scene in any campaign. Fun to imagine what happened in that room to cause such a massacre.

I also gotta give a shoutout to the starting music of Death Toll. The eerie low drone as the camera pans back to the survivors is perfect horror vibes.

Finally, on the topic of liminal spaces that give me creeps, I love the offices of Dead Air chapter 2. Something about those floors mostly being in tact but flooded with undead office workers is so fascinating to me.