From By pointzeroeight: Man of Mystery is actually really simple to unlock. You have to fill up your little bar on the side by clearing the same color a few times in a row. If you clear the color with squares, you get two blocks filled in for each square, so two squares = achievement unlocked. Any other type of group you clear will only earn you one tile in the bar unless it's got one of the giant Yosumin in it. Nothing random about it. One way to tell for sure you're doing the right thing, apart from the achievement unlocking, is that once you fill the bar, every yosumin of that color on screen will disappear.