Minimum of two, most eight
The rooms each have between 6 -8 slots for people. If you do not fill the room slots other people can join your room.
Minimum is 2, although for some rooms you'd want 3 or 4 to make it easier. I've seen a dozen people go into one room together, but honestly, after like 6 people it starts to get a little crowded. My husband and I did Knight and Rook by ourselves just fine, but we welcomed the help of 3 strangers in the pirate one.
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