The controls of Metroid Prime are unique, to say the least. The entire action unfolds from a first-person view, and since you're in a suit, it comes out of a visor. Note that you cannot alter controls beyond inversion of Y-Axis and Rumble features.
You'll notice that there are some lines running up the HUD. These lines light up when you take damage, otherwise they're just supposed to be lines which interlace to make a complete HUD.
Sometimes, a bar on the left center portion of the HUD will raise a bar and give an exclamation point. This is a threat warning — essentially, it warns you of environmental damage, such as fire, acid, poison, phazon, electrical output, or proximity to enemies.
- : Radar. It's self explanatory. Since Metroid Prime has a unique combat style, you'll be using it mostly to scope out enemies, not to really get a bearing on them. All enemies, unless cloaked or in a transdimensional state, do not appear on the radar as orange dots.
- : You'll notice a bar with a number. This is your missile count. It does not have a ratio, so you are unable to tell just how many missiles you've accumulated until you fill up. A message and orange lights appear when you're low on missiles, which is never a good thing.
- : Weapon selection. Samus does a pretty cool thing to change her weapons — she simply changes the shape of her hand. When you use the , you can alter your weapon. Initially you start out with the charge, and power beams. The charge is a simple power-up that allows you to do its titular function: charge. The power beam, represented as an orange hand, can be fired rapidly, when charged does decent damage, and is a good pot-shot weapon.
- : Visor selection. You'll notice you have two visors to begin with: combat, and scan. Combat is what you'll use about 70 percent of the time. The HUD as I explain it is combat mode, so there's no need to get into it. When in scan mode, you get a telescopic view of things, you drop your weapon, but are able to scan things that have orange or red squares on them. Use to switch over. Using the , and holding it down, you can scan objects. This is pretty essential, unless of course you're using a guide. By scanning, you can check for structural integrity, find weaknesses, interface with equipment, hack into computers, and unlock art galleries. By pressing or you can return to combat mode.
That about covers it for your HUD. But where are the controls? You'll notice you cannot alter controls beyond inversion of the Y-axis and rumble control. Metroid Prime is not a first-person shooter; it is an exploration and adventure game with action sequences. You must use everything at your disposal because the reality is you are not built like a tank. You are a mobile, agile hunter who must outwit your often overpowering and towering foes.
- : Basic movement. Samus is pretty responsive, but a bit on the slow side. Obviously tilting it gently invokes slow movement, tilting it forward causes you to run.
- : Visor selection.
- : Weapon selection. Cardinal directions.
- : Fire. Hold to charge, release to fire when you have the charge beam equipped. The can also cancel out your missile launcher, return you to combat visor if in scan mode, and lay bombs in morph ball mode.
- : Jump. When you have the space jump boots attached, you can do a double jump. An important feature of is that when in morph ball mode, and the proper equipment is attached, you may charge up your ball form, and boost. A super jolt of acceleration. Useful for getting out of harm's way.
- : Fire missiles. Missiles do good damage, and home when you lock on. When you get charge combos, press to release them. When in morph ball mode, use it to unleash a powerbomb.
- : Go into morph ball mode. Nobody else can do this: one of the many reasons Samus is amazing. When in morph ball mode, you are a metallic sphere composed of your same armor approximately 1 meter in diameter. You can roll around freely, so it is critical to learn the precision of the morph ball. You also will change to third-person view. When hitting , you are vulnerable for about a second, and when you revert to your normal walking state you are again vulnerable for about a second.
- : Toggle map. Under here, there is a FULL 3D map, showing off areas you've visited (colored orange) and, if you have the map of the area, areas not visited (colored light-bluish). Use the to rotate it in any direction and to look at different rooms; if the map has multiple levels, elevators connecting two levels will have an asterisk (*) on them, usually color-coded. You can also use the and to zoom in and out, respectively. Plus, the name of EVERY room will be shown when you center on it (center = highlighted rooms), excluding unvisited rooms. Finally, you can see the approximate location of the doors (also color-coded) in the rooms. For example, gray will be for missiles, purple for Wave, and so on. Note: the map will NOT show ledges/platforms within the room.
- : Free look. Hold it down ever so slightly to look around, while Samus grips her gun. If you depress it all the way, a targeting rectangle will appear. Not totally necessary, but you can sometimes get things from afar with it.
- : Lock on. The most important function in the game: scanning, combat, and your survival depends upon it. By holding it down in combat mode, you can lock onto things. Once locked, you can strafe or move sideways while facing the target. Combine jumping and targeting to do a quick dash, useful for dodging attacks. Used with the Scan visor to scan. When an enemy or item is locked on, a rotating targeting rectangle appears on it. By tapping it or "triggering" it, you can switch targets.
- : Inventory, Log Book, and Options. Inventory checks the status of the items you've obtained and equipped. Log Book gives you the information you've scanned, whether it be Chozo Lore, Creatures, Pirate data, etc.