Hey y'all!

I'm currently writing (with a friend's help) a oneshot rpg which has mainly a mystery/supernatural plot:

The characters find themselves in a secluded village, known for having a pitch black lake and iron deposits that explain this occurrence. While the townsfolk seem nice and celebratory, cryptic messages follow our characters to scare them away...

The story involves mystery and the supernatural. The pcs are normal people (in the sense that their abilities are pretty much what you would expect except for maybe 'spiritual powers' deriving from rituals and such.)

The supernatural aspect of the story involves a sort of Lovecraftian event, utterly terrorific, unexplainable, unavoidable.

I'm currently struggling with the system to run this oneshot. It's my first time writing something like this and I don't really know how to write these encounters and abilities etc from scratch. I would love it to be 'easy' but also dynamic and surprising.

I would deeply appreciate it if you have any tips for me and reccommendations on these matters!! :))

If I succesfully run the game I would love to share it and run it on roll20

thank you for reading this :)

Reiko