a grid of circles, either in a square pattern or a hexagon pattern - probably square
on each side (either 4 or 6 sides), you can rotate cirles left or right (for example, by clicking on a counterclockwise half-circle arrow in the right side of the circle or a clockwise half-circle arrow in the left side). the purpose is to match up the colors on each side to the colors on the adjacent circles' sides. (the program generates a random grid where they're all matched and then randomly rotates the circles.) the number of colors should probably be between 2 and 4.