One that uses only pre-made characters...like Slendy, Jans, Freddy, etc.
Paranormal
Something thats already been given a plot (like so-&-so decide to go to an abandoned building, etc. What do they find there & what happens to them? (ok lame, but thats just an example...)
Themed around some specific sort of monster likes zombies, vampires, serial killers
Dude...just think of something original... -_-
Holiday themed (whatever holiday is around)
Comment! (Because we love you from the bottom of our black little hearts...)
They all sound good to me. >.<
Last lines of the writing are already picked for you...The ending has already been decided.