Every level in the game besides the boss level has a safe with a password inside each one is a secret to collect.

Password	Effect
010213	Level 1-1 Safe
050886	Level 1-2 Safe
220584	Level 1-3 Safe
140783	Level 1-4 Safe
050715	Level 2-1 Safe
297414	Level 2-2 Safe
123456	Level 2-3 Safe
711825	Level 2-4 Safe
321310	Level 3-1 Safe
242526	Level 3-2 Safe
224445	Level 3-3 Safe
131825	Level 3-4 Safe
182124	Level 4-1 Safe
751125	Level 4-2 Safe
836773	Level 4-3 Safe
419715	Level 4-4 Safe