Amazing Penguin (Game Boy)

Amazing Penguin
Also known as: Osawagase! Penguin Boy (JP) Developer: Natsume Publisher: Natsume Platform: Game Boy Released in JP: August 8, 1990 Released in US: December 1990 Released in EU: 1991 This game has a hidden sound test. This game has a hidden level select.

Sound Test

At the title screen, press Select to highlight the password option, hold Left+A and press Start to enter the password screen, and enter 505050 (US) or B0B0B0 (JP) as a password.

Level Select

At the title screen, press Select to highlight the password option, hold Left+A and press Start to enter the password screen, and enter 303030 (US) or F0F0F0 (JP) as a password.

(Source: cah4e3)