Best Ending 
In Room 99, take the Crystal to Room A0. In Room B3, fire at the final enemy until
it's covered with a bubble. Now, press Start to bring in the second player. Pop the
bubble and you'll get the happy ending. 

Level Select 
To start on any level, enter the password "DDFFI". Move the cursor to one-player or
two-player continue, then press B to change your starting level. 

Passwords 
Level  Password
10     BCCCB
20     AFFFB
30     AGJJJ
39     IABBG
43     IEJJJ
58     FGJJJ
63     FJEEJ
77     JIAAI
81     CCJJI
99     NEJJJ

Or try these for the hard levels: JIACI, GGCAI, GGJBI, JFGII, CECAI, CBFEB,
CJGIB, CAFEI, CAIGB, CCEFI, CJEFB, CIEFI

Sound Test 
To access the sound test, defeat Super Bubble Bobble mode and get a happy ending. 

Super Bubble Bobble 
Enter the password HCICD. 

CODE	KEY IN . . .	EFFECT . . . 
1	PEXEEALA	1 life--player 1
2	TEXEEALA	6 lives--player 1
3	PEXEEALE	9 lives--player 1
4	TEVATZLA	6 lives--player 2
5	PEVATZLE	9 lives--player 2
6	SZNOASVK	Infinite lives--both players
CODES 7 AND 8: NOT ON THE 1ST LIFE AFTER A CONTINUE
7	LEXAUAPA + LESOZTPA	Start each life with 3 hearts
8	IEXAUAPA + IESOZTPA	Start each life with 5 hearts
9	OXXANUPX	Blow bubbles further
10	IEKEGZPA	Start on level 5
11	ZEKEGZPE	Start on level 10
12	YEKEGZPE	Start on level 15
13	GOKEGZPA	Start on level 20
14	POKEGZPE	Start on level 25
15	TOKEGZPE	Start on level 30
16	AXKEGZPE	Start on level 40
17	IXKEGZPE	Start on level 45
18	ZUKEGZPA	Start on level 50
19	YUKEGZPA	Start on level 55
20	GUKEGZPE	Start on level 60
21	PKKEGZPA	Start on level 65
22	TKKEGZPA	Start on level 70
23	LKKEGZPE	Start on level 75 
24	ASKEGZPA	Start on level 80