Key Code:
1 Up
2 Down
3 Right
]4 Left
5 C-Up
6 C-Down
7 C-Right
8 C-Left
12565247 Level 2
14565457 Level 4
16545864 Level 5
13565577 Level 9
24525781 Level 11
28361621 Level 13
26785545 Level 14
48585278 Level 16

To access the cheat menu, go to the password screen and press Left,
Up, C-Down, C-Left, C-Right, C-Up, C-Left, Down.