The second Metroid game, developed from the ground-up for Nintendo's black & white handheld, takes place some time after the NES original. Samus flies to the home planet of the Metroids, SR-388, an unstable place racked by earthquakes and torrents of lava. Many powerful breeds of Metroid thrive here and in the cavers below the surface. Samus roots them all out, eventually destroying the Metroid Queen. A baby Metroid hatches immediately after the battle and imprints upon Samus. Thinking Samus is her mother, it helps her escape. Samus then turns the hatchling over to the Galactic Federation, thinking that researching it might prove fruitful. Gameplay itself is classic sidescrolling, shooting, and puzzle solving, with plenty of alien encounters.