Do you have crossword puzzles in your country? In the US, the New York Times newspaper has a famous crossword puzzle. A new puzzle is printed each day in newpapers in many cities in the US. Monday is not difficult, but each day they get harder. Monday starts over again with an easy one. I usually can only do Monday and Tuesday. I have friends that can do every day's puzzle very quickly.
we have them here aswell in our news papers. I don't know if we have the same system of raising the difficaulty though.