Passing the Buck

Four forty piece jigsaw puzzles are muddled together and the pieces shared amongst the players.
Each player has a screen (like a DM screen in RPG's), with a colour picture of the Western themed jigsaw that they must race the other players to complete. Each person's puzzle is different, and so the players must swap pieces by bribery or auction style to win the pieces they need.
Because no-one can see the other players jigsaws, it becomes tense as the race to complete becomes frantic!