'O! EUCLID is "an amusing and scholarly card game for ages 9-99 according to the game box top.
There are 84 cards, 6 cards for each of 14 geometric shapes: circle, equilateral triangle, square, regular pentagon, regular hexagon, regular octagon, isosceles triangle, right triangle, rectangle, parallelogram, trapezoid, ellipse, parabola, and hyperbola. Of the six cards, one card shows the shape and its name; one card lists 4 questions (and the true/false answers) about the shape, and four cards each with a part of the shape so that when the 4 cards are placed correctly in a 2x2 pattern, a larger version of the shape is made.
Instructions include game rules for 4 games, of which Game 2 is the basic game. In this game players win by collecting the most complete sets of 5 cards (name card plus 2x2 pattern).
There is one instruction sheet for game rules. There is also one information sheet listing Euclid's definitions of geometric shapes and describing their mathematical characteristics. The information on this second sheet is not needed for game play.