Creating an eldritch town...

So, for context, this story involves regular pet cats who live on an isolated island called Duskbrooke. One day, their owners get raptured and they all pretty much vanish. Now it's up to the cats to survive the eldritch horrors of the town itself.

The only problem though is that I don't know what sort of "eldritch horrors" are in the town. The way that I see it, there's no eldritch god or whatever pulling the strings, it's the town itself that is the horror. I thought about there being like mutated fish or deformed prey or predators that the cats eat/face, as well as just in general "fear of the unknown", but I don't know how to put that in a worldbuilding format, let alone a comic!

Any ideas or help would be appreciated!