Horror based run, no, not those horrors from ED Options

[GM Lich]

So I’ve been running campaign for a while, We’ve had our pink mohawk moments along with with our trenchcoat moments. I’ve been leaning mostly towards trench coat. Now I’ve felt inspiration from the other campaign I’m playing in. What he did was basically sent a possessed vessel body. While that doesn’t sound that scary the way the GM did was great, we investigated a mansion. We learned about the history of the owner of the mansion. We then found the body, and bam, came to alive, the way the GM described it we considered not even fighting it. We thought it was rather hopeless, until we had no choice but to fight it. The idea was to fight it while the others found exit. Turns out it was only a force 5 so it died to focus fire.

So feeling slightly inspired by that GM’s horror idea, I’ve decided to make a “horror” based run.
The most effective ways I think is:
Isolation, this is a classic horror trope, losing contact with outside. So that means no matrix connection, if there is it is static at the best
Disarm the PCs, Horror isn’t that scary if all it takes is a couple of heavy weapons like Gauss rifles and take them on
I was thinking of perhaps placing them in an area where they can still use heavy weapons but if they miss it could easily doom them. Ex: A abandoned system of tunnels thats not longer structurally sound.
The Monster should be incomprehensible, the monster shouldn’t be able to be negotiated with, also the less they know about the monster the better. I’ve noticed in most media the less you know about the monster that is lurking about the scarier it is.
I would like to avoid using spirits against them for the sake of making not seem like I just copied the other GM. A little bit of magic to mess with them perhaps.

I’m still stuck on what I actually want to do, but I figured you guys may have some ideas.