Press Left, Right, Left, Right, Up, Down, Up, Down at the Galaga Arrangement title screen.

Pac-Attack: Level passwords:

Level Password
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