Optimal Upgrade Paths

Maximizing Samus's capabilities early on can significantly ease your journey through Sector 1, Sector 2, and Sector 3. While some upgrades are story-gated, many Energy Tanks, Missile Tanks, and Accel Charges can be acquired out of the way, providing a crucial edge against tougher enemies and bosses. This section outlines an optimal path for collecting these vital upgrades as soon as they become accessible.

Early Game (Sector 1 & 2)

Focus on bolstering your health and missile capacity before tackling major threats. These early pickups are relatively straightforward to obtain.

Energy Tank #1: After defeating the first large enemy in the Main Reactor of Sector 1, proceed through the newly opened door. The Energy Tank is directly ahead.
Missile Tank #1: In the Bioresearch Lab of Sector 1, after the first encounter with the small, crawling enemies, look for a hidden passage behind a destructible wall. Use a Charge Shot to break it.
Accel Charge #1: Located in the Waste Disposal area of Sector 2. After navigating the initial platforming section, you'll find it on a higher ledge accessible via a wall jump.
Energy Tank #2: Within the Desert area of Sector 2, after activating the first environmental control unit, backtrack slightly and look for a hidden alcove on the upper level.

Mid Game (Sector 3 & Post-Gravity Suit)

Once you acquire the Gravity Suit, new areas and previously inaccessible upgrades open up. Prioritize these to prepare for the challenges ahead in the later parts of Sector 3.

Missile Tank #2: In the Geothermal Power Plant of Sector 3, after restoring power, return to the central chamber. A new path will be available leading to this tank.
Energy Tank #3: Within the Lava Caves of Sector 3, after using the Grapple Beam to cross a large chasm, look for a hidden passage to your left.
Accel Charge #2: After obtaining the Space Jump in Sector 3, revisit the Main Reactor in Sector 1. Use your new ability to reach a high platform in the central area.
Missile Tank #3: In the Pyrosphere, after the first encounter with the large, fire-breathing creatures, look for a small opening in the ceiling that can be reached with the Space Jump.

Late Game (Post-Power Bomb & Screw Attack)

With the Power Bomb and Screw Attack, nearly all areas are accessible. This is the time to sweep for remaining upgrades, particularly those in previously explored zones.

Power Bomb Tank #1: In the Cryosphere, after activating the cold-generating machinery, a Power Bomb block will be visible in a previously frozen section.
Energy Tank #4: Return to the Main Reactor in Sector 1. Use a Power Bomb in the large central chamber to reveal a hidden path to this tank.
Missile Tank #4: In the Desert area of Sector 2, use the Screw Attack to break through a series of weak blocks on the ceiling, leading to a concealed room.
Accel Charge #3: After acquiring the Plasma Beam, return to the Bioresearch Lab in Sector 1. A previously impenetrable door can now be opened, revealing the Accel Charge.

Remember, consistent exploration and revisiting areas with new abilities are key to a fully upgraded Samus. Don't hesitate to consult your map for unexplored sections or hidden pathways indicated by suspicious cracks or unusual environmental features.