The daily coin puzzle. Give the tray what it wants: move a coin into each Wanted space, then resolve the rest so every coin left on the tray is in a valid group.
Valid groups are always three or more coins. A run: in numerical order and the same metal. A set: of the same number and different metals. Groups can come apart while you work; they only need to be valid when you finish.
A new tray every day, in easy, medium and hard.