That was cool! The art is proficient, and the character design is charming. I like the jaunty level tune. It was particularly satisfying to scare the children away!
I'm not sure if I understand the stats for each decoration. According to the shop, the Skeleton and Mummy cost the same and have the same range, but the Mummy is more spooky. The Tombstone costs more than Lanterns, but is less spooky. Is there a particular mechanical reason to purchase the Skeleton or Tombstone? I hope I didn't miss something; it seems like a strange oversight.
The "scared" sound can stack endlessly when multiple children get scared off. It can get quite loud!
If Halloween arrives while the "Skip to Halloween?" prompt is up, it will stay on the screen with no way to remove it.
All-in-all, good work!