Easy to understand but difficult to solve, this little tile puzzle is guaranteed to live up to its name.
You get 16 different tiles, each divided into 4 yellow or blue-colored regions. "All" you have to do is slide them onto a 4x4 board so that blue touches only blue, yellow only yellow. There are 800 solutions . . . GOOD LUCK!
Although accessible to children, this puzzle touches on ideas from binary numbers to artificial intelligence.