At a costume party the opener is standing in front of you: ask about the costume, then ask about the worst one they ever wore. Most people have a story about a costume that fell apart or had to go under a winter coat.
Candy questions work across ages because everyone has an opinion. Kids can rank the candy from their own bags while adults remember the house that gave out full-size bars.
Later in the evening
Save the scares group for when people are sitting down, lights low if you like. The last three questions, about haunted places, things people can’t explain and horror movies that stuck, are for adults and older teens. If a younger child is in the room, stay with ghost stories and childhood fears that seem funny now. For a fire pit or a sleepover, the campfire questions go well alongside these.
A family Halloween at home
If you are carving pumpkins or handing out candy, ask a grandparent the questions in the last group: whether Halloween was a big deal where they grew up, what school parties were like, who made the treats. Their Halloween may look nothing like the one the kids know.
For a bigger crowd, the party questions and party games for adults give you more to work with.