I do not understand that much on this problem stated above
Hey! Thanks for the question!
The jam is for horror-themed, weird and spooky games specifically, but every jam we also have an optional theme that you can base your game around if you like! This jam's optional theme is MACHINE.
- SCREAM CATALOGUE
so either i can make a horror game or a game based on theme "machines"?
You got it! All games should be horror-ish, but you can also specifically focus on a horror game that is about machines :)