Crystal Quest [Model DMG-CQ-USA]

Secret options:
There a few secret options that can be accessed via the secret button codes listed in the table below. All must be entered at the title screen. You could have only one option at a time before the game. But enabled options are kept permanently even after the game over.
Up, Up, Up, Down, Down, Down, Left, Right - Starting Wave select (up to 40).
Left, Right, Left, Right, Up, Down - Shot mode select.
Down, Down, Down, Up, Up, Up, Left, Right - Ship speed select.

Continue:
When the game over message is displayed, press Down + Select + Start.