I hope it feels sufficiently "Halloween-y". I get that you don't want to repeat yourself too much, but I think "Halloween" always works pretty well as a theme. I always love when at least one part of the event is connected to the actual imagery and aesthetics of the holiday. Pumpkins, graveyards, autumn colors. The event just doesn't feel right without it; it's just a bunch of vaguely horror-adjacent concepts without that seasonal core to tie it all together.