Furd Herder mini-game
Enter "Green Alien", "Green Alien", "Square", "Green Alien" as a password to unlock a Minesweeper-like mini-game.
Snake mini-game
Enter "Circle", "Diamond", "Square", "Green Alien" as a password.
View Klax history
Enter "Yellow Alien", "Pillar", "Pillar", "Green Alien" as a password.
View Klax myth
Enter "Square", "Pillar", "Diamond", "Green Alien" as a password.
View programmers
Enter "Green Alien", "Green Alien", "Circle", "Square" as a password. Note: A Game Boy Printer is needed for this trick.
View credits
Enter "Pillar", "Yellow Alien", "Diamond", "Diamond" as a password.
Programmer screens
Enter "Green Diamond", "Pillar", "Pillar", "Green Alien" as a password. Ignore the error message and enter again until it has been done ten times. A series of screens will appear. You can also enter "Red Circle", "Pillar", "Pillar", "Blue Square "as a password ten times.
Adventure mode (European version)
Enter "Square", "Yellow Alien", "Green Alien", "Yellow Alien" as a password.
| Level | Password |
| 1 | Yellow Alien, Pillar, Pillar, Circle |
| 6 | Circle, Yellow Alien, Square, Yellow Alien |
| 11 | Yellow Alien, Yellow Alien, Square, Green Alien |
| 16 | Diamond, Yellow Alien, Green Alien, Diamond |
| 21 | Diamond, Square, Diamond, Green Alien |
| 26 | Pillar, Yellow Alien, Square, Pillar |
| 31 | Green Alien, Circle, Pillar, Pillar |
| 36 | Circle, Circle, Yellow Alien, Yellow Alien |
| 41 | Pillar, Diamond, Diamond, Circle |
| 46 | Yellow Alien, Diamond, Circle, Pillar |
| 51 | Square, Diamond, Yellow Alien, Square |
| 56 | Pillar, Square, Square, Yellow Alien |
| 61 | Circle, Square, Circle, Green Alien |
| 66 | Circle, Diamond, Diamond, Green Alien |
| 71 | Circle, Square, Square, Pillar |
| 76 | Green Alien, Green Alien, Yellow Alien, Circle |
| 81 | Pillar, Circle, Circle, Pillar |
| 86 | Square, Green Alien, Diamond, Circle |
| 91 | Yellow Alien, Green Alien, Circle, Diamond |
| 96 | Pillar, Pillar, Green Alien, Square |
