Set (card game)

is a real-time card game designed by Marsha Falco in 1974 and published by Set Enterprises in 1991.

The deck consists of 81 unique cards that vary in four features across three possibilities for each kind of feature: number of shapes (one, two, or three), shape (diamond, squiggle, oval), shading (solid, striped, or open), and color (red, green, or purple).

For each one of the four categories of features—color, number, shape, and shading—the three cards must display that feature as either a) all the same, or b) all different.

The game evolved out of a coding system that the designer used in her job as a geneticist.

Additional variants continue to be created by avid players of the game.

A group of people at a table playing set
Playing Set
A complete set of 81 cards isomorphic with those of the game Set showing all possible combinations of the four features. Considering each 3×3 group as a plane aligned in 4-dimensional space, a set comprises 3 cards in a (4-dimensional) row, with wrap-around. An example 20-card cap set is shaded yellow.