After completing the game once, hit the R button to unlock World 9 and a sound test and Boss mode
Complete Boss Mode once to Unlock the final secret stage World 10
In order to battle against the boss in World 10 you must complete the following levels within a certain time limit. 10-1 - 45 seconds 10-2 - 2 minutes 20 seconds 10-3 - 3 minutes 50 seconds 10-4 - 2 minutes 10 seconds 10-5 - 2 minutes 50 seconds 10-6 - 2 minutes 30 seconds
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