Star Wars (Game Gear)
This game has a hidden level select.
At the title screen, press Right, Up, Down, Right, Up, Down, Right, Up, Down, Right, Right, Right. The music will change to confirm correct entry. Start the game and clear level 1. On level 2, lose all of your lives. The level select will be on the continue screen. Press Left and Right to toggle the level to go to, and choose Yes to go there.