KungFu Kickball

To get this achievement, you will have to play through all six stages of "Arcade" as the last stage can't be accessed until you have beaten arcade mode. It should pop once you start playing the arena titled "Final Stage."

You shouldn't have to finish the level, but I recommend playing it all the way through and winning so that you can also unlock the difficulty related achievement(s): White Belt (Apprentice), Green Belt (Teacher), Purple Belt (Master), or Black Belt (Grand Master). You can't get Black Belt until you beat "Arcade" on Master Level. Also, if you play on a harder difficulty, the easier difficulty achievements below it should pop as well.