Once you enter the map screen, go to the level on the right. Now progress your way through the map and clear the first castle. In the level after the castle, you'll grab Yoshi at the end and jump off Yoshi when you see the dashed block marks. Wall jump up to the switch and reveal the key hole, which will take you to a secret exit. In the secret water level, grab a propeller in the bonus area which can be accessed by entering the blue pipe after a row of question mark blocks. Do not take the secret exit; take the regular one instead. You'll now have unlocked a ghost house. There's a glitch in the ghost house. You need to get both the normal and secret exit to activate the star launch pad. After you get both exits, take the launch pad and complete the first four star world levels with secret exits. Then go to the last launch pad you unlocked and you can access Bowser's Castle. The run: