Codes and passwords
Password - Effect
098654 - 10 extra lives and 50 keys
736353 - 10 extra lives, 50 keys, 50,000 credits
378829 - Fifty keys
193831 - Unlock level 10
090921 - Unlock level 11
309383 - Unlock level 12
101221 - Unlock level 13
103992 - Unlock level 14
998112 - Unlock level 15
125332 - Unlock level 16
091233 - Unlock level 17
353828 - Unlock level 2
108383 - Unlock level 3
370101 - Unlock level 4
982822 - Unlock level 5
847464 - Unlock level 6
737373 - Unlock level 7
928112 - Unlock level 8
267364 - Unlock level 9