Play hide and seek with a spirit in a barrel.
This is based on the Shirlock Holmes: Nemesis Creepy Watson glitch.
Don't worry about the amount of effort I put in, it was a mostly a free asset pack. It even came with the room pre-populated. all I did was make the walls solid, add a player object, and make one barrel haunted. It took about 5 hours.
Find the haunted barrel and click on it to see if you are right.
This was more fun than I intended.