RufasCube is a slider puzzle where there is a 3x3x3 arrangement of cubelets with the center one missing, allows sliding permutations. After a randomization, the goal is to restore the cube to its original configuration based on color and alphabetic hints. It is challenging, but not as difficult as a Rubik's cube. Here, diligence pays off. Also, incremental solution is possible - you can unscramble one slice at a time. When you finish, you can see the entire English alphabet appear on the 26 cubelets. It supports laptops and Mac Retina displays.
