Kabuki

There are four actors and ten different masks, each with several copies. Prove yourself to these great actors by giving them sets of unique masks, taking it in turns to turn over one mask-card and placing it on-top of the pile of masks of one of the actors. If you remember seeing the same mask earlier in a pile as another puts a mask on, stop them! If you’re right, you’ll get to take as many coins from them as there are repetitions of the same mask on that actor. If the accuser is wrong however, they lose a coin.