13 Ship mode
Successfully complete Extra mode. You can now select "Configuration" at the "Option" menu" and set your number of ships to 13. Note: You can also change the order of the ships under a special setting when 13 Ship mode is enabled. Also, you can only use one credit in 13 Ship mode.
Successfully complete Arcade mode or Extra mode. You can now select "Configuration" and access the "Stage Select" option at the "Option" menu.