Halley Wars (Game Gear)

Halley Wars
Developer: I.T.L Publishers: Sega (US/EU), Taito (JP) Platform: Game Gear Released in JP: June 21, 1991 Released in US: 1991 Released in EU: 1991 This game has a hidden sound test. This game has a hidden level select.

Halley Wars is a sequel to the 1986 arcade shoot 'em up Halley's Comet. It was also previously released for the Famicom Disk System.

Extra Options

At the title screen, press Left, Left, Left, Left, Right, Right, Right, Right and then start the game. The menu will now have a level select and sound test added, plus settings for speed, weapon level, and lives.

(Source: GameFAQs (Mesmorize99))