Silpheed/Codes

SEGA CD
During the game's intro, pressing down, down, up, up, right, left, right, left, buttons a, b, and start on the controller will take the player to the stage select screen.

The game only has 12 stages, which selecting any number over the stage of 12 will show the cutscenes and other bonuses, such as various ships that are seen in the backgrounds of the game.