Sudoku puzzles became popular in Japan but wouldn't catch on in other places for a few decades. By the early 2000s, sudoku had made its way back to the Western world as newspapers began including sudoku puzzles alongside other games. Sudoku became very popular with puzzlers, and the rest is history.
By the way, the word sudoku is made up of two kanji characters - su, meaning numbers, and doku, meaning single or alone. The word can be interpreted as meaning "Only single-digit numbers can be used" or "Numbers can only be used once." Today, the word sudoku has come to be known and understood throughout the world.
