I have been checking/playing other entries. I haven't seen another horror game yet. Who else made a horror game?
This is mine by the way;  (play with earphones)

https://itch.io/jam/gmtk-2019/rate/461703

I think my project can named horror https://itch.io/jam/gmtk-2019/rate/462518

Our game is a horror shooter https://itch.io/jam/gmtk-2019/rate/463759

Hey,
Our game has darker atmosphere and huge cockroaches, spiders. So I think it fits a little bit into the Horror category :D
Check it out if you're interested: https://itch.io/jam/gmtk-2019/rate/463156
Here's some screenshots:

https://becher.itch.io/light-them-up
We made a Survival Game in a dark and secluded space, I don't know if it fits your horror definition but it sure is oppressing.

Mine wasn't planned to be horror game, but a lighting problem and a lack of time to make levels kind of drove me in that direction. Quite happy with it considering how much my plan changed from a platformer fps to this!

https://jotlane.itch.io/one-leg

My game is a Horror Adventure game where you control a Robot through Text Commands in order to make a cure to an Infection that is slowly killing you - https://itch.io/jam/gmtk-2019/rate/462295

We made some kind of "horror", if you are interested:

https://itch.io/jam/gmtk-2019/rate/461557

Comments and rate are very welcome :P DO IT! 

Here is mine: https://itch.io/jam/gmtk-2019/rate/461862

There is a bit of silliness to it but some have said it is scary so check it out if you get a chance :)

Dude, I made a "RPG", I think I'm alone in this world

Does a mosquito buzzing next to your ears count as horror?

https://mikeyren.itch.io/onlyone