Each different element needs something coming from the headstones.Books- Twilight (all the creepy twilight books that have come out now)
Film- Starwars (wookie), Mary Poppins, LOTR
Music- Elvis, Rebecca Black, Auto-tune guy "they be snatch'en your people up"
Also, a lot of times you can make people more interacted when you add easter eggs, or parts that aren't necessary but are kind of fun. For instance, I've made it so when you click on one of the headstones in the background a zombie pops up moaning "zombie web."
