When I went, we did the mafia room. Most of us were older than 15 but we brought my 5 year old sister in law and she had a ton of fun. She even found some important things for us :) We were still able to finish the room within 38 minutes (out of 60). So, I would say anyone any age can enjoy it, but I agree with Andrew that there are some clues that younger children would never get and would need help from teens or adults. In the mafia room there is a gun and alcohol bottles (props) - so some parents may want to be with their kids to explain these things.
I would venture from early teens on up. The content wasn't particularly inappropriate, but the puzzles are difficult. Some puzzles also require historic knowledge. A clever 12 year old may not have the best of times.
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