Play "Pin the Tail on Mrs. Norris" blindfold game.
Have a scavenger hunt using a Marauders Map made with invisible ink.
Hold Professor Trelawney's Divination Class and tell each other's fortunes.
Have a "Caring for Magical Creatures Class" that includes going to the zoo or pet store.
Hold a Tri-Wizard Tournament (draw out names in a goblet), solve riddles, run an obstacle course.
Play Hogwarts Twister using your own mat and a cube with hands and feet drawn on it.
"Niffler's Game" — hunt for buried treasure or Golden Snitches hidden in popcorn.
Wizard Hat Game — play ring toss into a witch's black hat or wizard's cap