Samus's 'build' is defined by the abilities she reacquires. These include Beam upgrades (Charge Beam, Wide Beam, Plasma Beam), movement upgrades (High Jump, Space Jump, Speed Booster), and utility items (Morph Ball, Varia Suit, Gravity Suit). Each ability opens new paths and strategies. The order in which you acquire them is largely fixed by the story, but understanding their utility is key to efficient exploration and combat.
