Galaga Arrangement: Display game time:
Press Left, Right, Left, Right, Up, Down, Up, Down at the Galaga Arrangement title screen.

Pac-Man: Pac-Attack game:
Select Pac-Man at the games screen. Get over 25,000 points during game play to unlock Pac-Attack at the games screen. 

Ms. Pac-Man: Pac-Mania game:
Select Ms. Pac-Man at the games screen. Get over 20,000 points during game play to unlock Pac-Mania at the games screen. 

Pac Attack level Codes

1 STR
2 HNM
3 KST
4 TRT
5 MYX
6 KHL
7 RTS
8 SKB
9 HNT
10 SRY
11 YSK
12 RCF
13 HSM
14 PWW
15 MTN
16 TKY
17 RGH
18 TNS
19 YKM
20 MWS
21 KTY
22 TYK
23 SMM
24 NFL
25 SRT
26 KKT
27 MDD
28 CWD
29 DRC
30 WHT
31 FLT
32 SKM
33 QTN
34 SMN
35 TGR
36 WKR
37 YYP
38 SLS
39 THD
40 RMN
41 CNK
42 FRB
43 MLR
44 FRP
45 SDB
46 BQJ
47 VSM
48 RDY
49 XPL
50 WLC
51 TMF
52 QNS
53 GWR
54 PLT
55 KRW
56 HRC
57 RPN
100 LST

Gameshark codes

[M] Must Be On 97263383C382 80AB66ACE8AB 95FF45E80A89
Ms. Pac-Man: Infinite Lives 87C48DD5248D 91F484D30791
Ms. Pac-Man: Start With Hi-Score D319D7D6E829 D25567E6B517
Ms. Pac-Man: Max Score 0D60981107DA D1F404210753
Ms. Pac-Man: Max Total Score C5AE08294262 193A941942EB