Be able to practice any bonus round
  There is a "Border Line" score in each level. Beat it, and you will get a
  marker on the level you did it for. Do this for all 10 levels, and a bridge
  will appear to Level 11. Beat the high score on Level 11, and it will give you
  a message. Press A while on level 11, and you will be able to practice any
  bonus round.


Hint by Felipe Gerhard - felipe.gerhard@gmx.net