So here's my idea. I like the cute characters in Monster House and Grabbed by the Ghoulies. Also the music from the Nightmare section of Pinball Dreams is another inspiration. https://www.youtube.com/watch?v=_lMC-vxcF4c

As the monster you own the house ( think Dungeon Keeper ). At first a lone kid enters looking for the treasure. Using pathfinding the kid will move through the house to collect the treasure then escape. If any loot is taken the level is lost. You have a range of ways to stop this from happening. Scaring, traps, blocks (to delay - lock the door), divert (open a door and offer something better than the treasure to lure them) and attacks. You are corporeal (ghost) for most of the time and move things around, but you can manifest in physical form to do physical attacks only when you have sapped enough fear from the kid. Rinse and repeat for each new level, but the difficultly is introduced by adding more kids at the same time, more treasure to lose (any 1 loss of treasure is a fail) and any kids who survived a previous level gets a +1 against fear next time, making them harder to scare.

Hi, we are playing around with a street scene in which kids are trick or treating. As a monster you are not after the candy, but after the kids!. Here's what we've got so far: WIP, you are the monster

Here's an update on my game. In this video the npc enters the monsters home looking for treasure. The AI selects the closest next room to search. Once it's been there it doesn't consider it worth entering again and looks for the next closest unvisited room. When it finds the treasure it steals it and heads out. The skulls above it's head are scare points. You need to scare it to avoid losing your treasure. More to come. Youtube -> WIP NPC Actions 1

@Mauro Hey - I need a monster roar/growl and swish for when the monster slashes at the player please.