There are not a ton of things for younger kids to do in the evening around Billings, but I found five that I would feel 100% comfortable sending my 6 and 11-year-old kids to go do with a responsible babysitter.
Have you tried one of Billings escape rooms yet? I have not. From what I gather, you and your teammates are locked in a room and have one hour to escape. We've got one booked for my kids birthday party this week. Stay tuned for a full review!