Metroid is an action-adventure game in which the player controls Samus Aran in sprite-rendered two-dimensional landscapes. The game takes place on the fictional planet of Zebes, a large, open-ended world with areas connected by doors and elevators. The player controls Samus as she travels through the planet’s caverns and hunts Space Pirates. She begins with a weak power beam as her only weapon, and with only the ability to jump.
The player explores more areas and collects power-ups that grant Samus special abilities and enhance her armor and weaponry, allowing her to enter areas that were previously inaccessible. Among the power-ups that are included in the game are the Morph Ball, which allows Samus to curl into a ball to roll into tunnels; the Bomb, which can only be used while in ball form and can open hidden floor/wall paths; and the Screw Attack, a somersaulting move that destroys enemies in its path.
In addition to common enemies, Samus encounters two bosses, Kraid and Ridley, whom she must defeat in order to progress. Ordinary enemies typically yield additional energy or ammunition when destroyed, and the player can increase Samus’s carrying capacities by finding storage tanks and defeating bosses. Once Kraid and Ridley have both been defeated, the player can shoot their statues to open the path to the final area and confront the Mother Brain