The tiles are all the combinations of straight, convex and concave edges, transformed step by step from a regular square. The 36 tiles comprise the 24 permutations of hearts and spaces, plus 12 duplicates, divided into three colors. We combine three colors (Lucite), sometimes mingled with black, to give the all-acrylic set a stained-glass look. It looks really nice displayed on an easel. (Some people think of Escher.) The tray is 8½". Hundreds of symmetrical figures to solve and rules for 7 original competitive games are also included, for 2 to 6 players, ages 12 to adult. $65

One of our most sophisticated sets. The 12 all-different acrylic tiles (sample shown at right) are hand-inlaid with three colors that evoke the optical illusion of three-dimensional shapes. They can form gorgeous designs where colors match and flow between tiles. Two games involve joining tiles to score points by matching and extending (or blocking) a color. For its 25th anniversary in 2012 we introduced new frosted colors. You can order your preference of bold, blue ice, and pool colors. For 1 to 4 players, ages 8 to adult. $65

Nine easy pieces—shapes made of 2, 3, 4 and 5 equilateral triangles joined—fill the encircled pattern and form a large variety of shapes outside the ring, too. For the toughest challenge, have no two of the same color share sides. A computer search by Bill Cutler proved that only 2 solutions meet this condition...out of the 15,140 different ways to fill the circle! We had offered this challenge as a contest for the International Puzzle Party in 1997, and Bill's findings won the prize. All acrylic, five-color mix in a 5½" tray. For 1 or 2 players, ages 6 to adult. $29

Here's a novel concept: 24 diamond-shaped tiles and 6 triangular tiles carry the 6 dominant rainbow colors in every combination (one sample shown at right). Join them so colors meet only their own shades or their neighbors in the spectrum. Patterns emerge as you rearrange the tiles. Illustrated booklet shows many interesting shapes to solve outside the 8½" tray, as well. It's proven to be one of our instant hits for all ages, 5 to adult. All acrylic, for 1 or 2 players. $65