Kuusou Kagaku Sekai Gulliver Boy: Kuusou Kagaku Puzzle Purittopon

Kuusou Kagaku Sekai Gulliver Boy: Kuusou Kagaku Puzzle Purittopon
Publisher: Bandai Platforms: Game Boy, Super Game Boy Released in JP: April 28, 1995 This game has a hidden level select.

Level Select

At the title screen, hold Up and press A x12. A sound will confirm correct entry. Start the game, pause, and press Select to change the level number at the bottom right of the screen. Unpause to go to the chosen level.

NOTE: The level select will only work in Story Mode (first option) and Puzzle Mode (third option).

(Source: Game Tricks Encyclopedia Wiki)