Simple rules make these games pleasant to play. The variations among them are very minor when present at all. On a turn, a player places one piece of his/her color on any vacant space of the multi-level board. The object is to place three or four pieces in a straight line. The line may be vertical, horizontal, or diagonal. The line may be confined to one level or it may run onto all three or four levels. These games are basically two-player games; although, some variations give rules for four or more players. Over the years, Qubic has been the most popular of the bunch.