sudoku craze on ny subways

Have you played Sudoku yet? I found a puzzle while riding the PATH train yesterday. In one of the free subway newspapers, AM New York, I think it is called. I have seen people erasing and writing like mad in their little Sudoku books. I have seen people walking and playing while transferring from the G to the E at Court Square. So I thought, ha! Now I can see what all of this is about.I liked it.