Rubik's Cube and the 14-15 sliding square puzzle are the most popular mechanical puzzles of the 20th and 19th century, respectively. What could be more obvious than combining those two great ideas?
Here you see the resulting combination, a 2x2x2 Rubik's Cube with sliding square faces. The object is to scramble the puzzle and then to twist & slide the tiles back to their original position and orientation.