First Visit - Arrival
As you arrive on the planet, you will land your spacecraft in a convenient open area called Crateria (like a crater). Save your game now to avoid any mishaps (press down while standing on the top of the spaceship). Run to the left, shoot the door and enter. You will notice little bugs around, they are the butterfly's of Zebes. Continue to the left (hop over the mound) and then down the pit to the very bottom. Jump over the blue door, hold down and fire to open it (or aim diagonally down and fire).
Upon entering you should notice the blue clouds floating around, signifying the desertion of the area (also note the cracks on the tiles and walls); this is obviously an old place.
Make your way to the bottom of this tall room (stay to the far right as much as possible, there's a hole that will allow you to fall about half way) and continue through the door to the right. As you enter, you'll notice that the door behind you becomes gray (it has been disabled and you cannot exit). Also note that you are standing where Mother Brain was located in the first Metroid title.Continue to the far right, and head through the blue door; use the elevator pad and travel downwards. You will travel down a large tube and find yourself in the starting area of the original Metroid game! Make your way to the left (the right is a dead-end), hop up the steps and fall down the hole. Jump up and grab the Morph Ball; press to continue after the music ends.
The world immediately springs to life; the eye on the wall to your left will open and shine light wherever you move (within a certain range of it) and the two little faces near the podium will illuminate and turn to face towards it.
It's time to leave, so move to the right; you can't normally jump up the way you came in but it is possible to wall jump it. Notice the little block at the bottom of the podium, it's blocking your way so duck and shoot it to destroy it. Morph into a ball ( ) and continue to the right. Press jump or up to get out off the Morph Ball mode.
Missile Upgrade #1
From the elevator, move to the far right, and head through the blue door. You can't go through the pink door (you must use a missile to unlock it). Notice the cracked blocks, you can shoot at them diagonally or from up above to destroy them and then continue down. Morph into a ball, head towards the blue door on the left and then change back and head through.
You are now in a Chozo area, notice the ground and walls, this is uniform for almost every Chozo area. Shoot the glowing orb it is holding to reveal the first Missile Tank; jump up and touch it. After the music stops, press Start to continue. Missiles are now enabled! Press to enable the missiles, notice the barrel of your arm cannon opens to signify the change in weaponry. Do not waste ammo now, continue back out the door you came in.
Roll to the right, head upwards, jump on the first block platform, and fire straight up. Jump up, morph into a ball on your way up and continue to the right (this might take some practice, but go ahead and do so now, you'll need the skill).
Select your missiles, fire all five at the pink door to unlock it permanently (you will never have to waste another five on that door), continue to the right.
Missile Upgrade #2
Continue back to the left, through the door, across the cracked blocks and through that door. Now head back up the elevator shaft (notice the faces turn towards you as you move upwards).
As you arrive back in the chozo-like area, it is now lighted and much more warm, as you'll soon understand.
A Hostile Presence
Head through the door. Immediately you'll be introduced to your first foes: Space Pirates. Use one (1) shot to take them out. Note that they can leap off of walls and fire lasers from their forehead, eyes and chest.
Make your way to the left, killing all of the Space Pirates in this room so that you will be able to open the grey door at the leftmost side of the room. You may notice objects that appear after their destruction, these will be either ammo or health. Health look like pulsating purple circles and ammo will either look like missiles or metal orbs (power bombs, later on).
Go through the previously locked door, it's flashing gray/blue. Make your way back up the long room, kill all of the mantis-bots (they will probably be an annoyance if you don't, falling here is a real pain). They are easy to dispatch of if you jump up from below, and fire at their feet to avoid any lasers.
After you make it to the top, head through the blue door. Now that the world is "alive," monsters roam it. You immediately see a ground scrub guy, who simply runs around the edges of the room, it only takes one hit to kill and is easily avoidable (but killing is often the better choice, since they may follow you around a room and cause problems).
Head up, ignore the first blue door on the left (you need morph ball bombs for that), and go through the pink door on the right. Move to the right, destroy the little fly bugs (1 hit kill) and the yellow ceiling guy (4 shots), and continue to the right and through the door.
Map Station #1, Crateria
Move to the right and run into the map station, you'll attach your arm into the device and collect all of the general map data for this area of the world.
You will then be taken to the map screen (available by pressing ) where you should notice things such as the glowing area (your location), the M (Map Station), the S (Save Station), your ship (also has an S for Save Station), the locations of other regions (Brinstar, Wrecked Ship, Maridia), and the areas of the map with a dot within them (items of interest/upgrades).
Head out to the left, kill the enemies and head through the door.
Continue up, head through the blue door on the left that you have to roll to get to. This is a Save Station, enter it to be asked whether you want to save or not. Select Yes and press to save your game.
Morph Ball Bombs
Head out and continue to the top area. Move to the right, taunt the drill bats to dive or shoot them, continue to the right and roll down into the hole within the mound. You cannot return back up at this moment (the exit is blocked by morph ball bomb breakable blocks). Head to the bottom and through the blue door to the right. Make your way right killing all the flies from far away (a swarm can be nasty). Continue through the pink door.
An Unexpected Foe
Run to the left corner and wait there. The chozo's armor begins to crack, and fall away, before it awakens. The statue reveals its true nature as Torizo, the miniboss for this section. Begin attacking after it stands up and gets close to you, its stomach will begin glowing so switch to missiles and unload on its weak point (its stomach), switch back and just keep attacking until its stomach explodes (40 shots or 8 missiles). The chozo will follow a pattern in which it walks forward, stops, continues until it hits you, claws at you, jumps back, fires explosive orbs from its mouth and then repeats (although it might fire arc beams at you if you duck). Just attack it at all times, avoid the explosive orbs by either getting close, jumping over them from left to right, or wall jump off the left wall.
Eventually the stomach area will explode, you know you're making progress now. It will begin dripping spit like fluids at all time from it (aesthetic effect), just continue fighting. Its head will explode after 10 shots (if you can get a missile power up from destroying the orbs, you can waste him with just two missiles), you're getting close, just avoid getting hit. He no longer can shoot orbs so he will only patrol back and forth trying to claw at you. If you get close, he'll swipe with his arm, but you can use this to your advantage by running close, moving away then firing so that you have more time. The best strategy though is to move to one side, fire, when he gets close jump up over his head (preferably a wall jump to avoid damage) and then run to the other side and repeat until dead. He will explode after five shots (1 missile). This can be known as the mini-boss of Crateria although Crateria doesn't have a boss.
Detour For Missiles #3 and #4
Before progressing to Brinstar, you can pick up two Missile Tanks nearby thanks to bombs. First, to get out of the boss room with Torizo (where you got the bombs), just take the upper right path, utilizing the morph ball. Now that you have bombs, you can easily bomb away the obstructions. The blocked left path leads to progress, but you can opt to fall back down the shaft on the left, ending up at an area with two doors across from each other. The right was a red door leading to a map station, though you may have activated it already. The left, though, leads to a tunnel you can get into in your morphball form. You'll be stopped by blocks when you move left while morphed, but just bomb them away and continue. The door at the end of this path leads to a chozo holding a Missile Tank.
To get one more Missile Tank close by, head down the bottom blue door and down the shaft with small platforms again. Go right, and as soon as you enter this room take out the space pirate. Now, in the center of this platform you'll see a mess of tubes. Morph into a ball in the center and lay a bomb, and part of the floor should be blown away. You'll have to bomb twice more, then just roll in either direction. You should see the Missile Tank in plain sight. If you care about 100% completion, you should now be at 20 missiles before heading on.
Your journey continues in Brinstar.
Return to Samus' Ship
The upper path to Crateria has Scisers circling platforms, which are basically upgraded Geemers. A single grapple shot takes them out quickly. At the top of this area, shoot away the ceiling. Kihunters are found here. Head left, to reach a room like a pipe with windows. Begin dashing left in this romm, and you'll Speed Boost through a section of the wall in the next area. You're back where Samus landed in the beginning, where you can stop your run upon reaching your ship. You can recharge everything at the ship, and you have the option to save.
Now, the next necessary area is the Wrecked Ship. With your new items, however, you can decide to pick up a few extra things like Missile and Energy Tanks before that, if you'd like. If you want to do that, continue reading here.
Optional Items in Crateria
To start with, you'll need to perform a diagonal Shinespark in the area with Samus' ship. Perform it the same way as a normal Shinespark, but hold default to aim up diagonally before jumping when the boost is charged, making sure you press nothing else or you may go straight up instead. If done right, you'll Shinespark diagonally in the direction you're facing.
To get to the first secret area, Shinespark diagonally right before the left part of Samus' ship, on the right side of the little hill before it. If done correctly, you should end up near an orange door to the right which you can Power Bomb and enter.
The room here has acid moving up and down constantly, with blocks containing spikes sticking out from the ceiling, encouraging you to jump carefully when you go right. If all that's not enough, you should still take your time, because green Alcoons will jump from below on the small platforms. They're a small upgrade from the Norfair variety, but Missiles will end them quickly. Keep in mind the tops of the square blocks are safe from the rising acid, so no need to feel rushed. At the end, a pack of Power Bombs is the prize. Exit left.
Now, you need to get to the upper left area directly across from this cliff. Do a Speed Boost and jump left before the edge of the cliff to get there. You can Boost from the right room to activate it sooner, giving you a bit more leeway. When you reach the left side, you might break part of the cliff. Otherwise, if you end up on the top area, go down to the lip of the lower cliff, right before the edge. Either way, use a Power Bomb to clear the left path, and go through the door.
Rising acid in here again, with Yapping Maws as enemies. The square shaped sections in here can be gotten rid of with Power Bombs, so keep heading left and Power Bombing to clear the way. The Yapping Maws can be frozen, or Super Missiled to kill them for good.
Don't worry too much about taking damage in here, though, because in the left room you'll get an Energy Tank. In this room, use a Power Bomb to reveal an area below which you can head through as a ball. Continue left, again Power Bombing the obstructions. You'll see a part of the wall with upper and lower spikes blocking the way. Just use a Power Bomb here to blow away the spikes, letting you pass to the next room.
Shoot to clear away some of the left wall. In here, there are essentially two sets of crumbling block paths on the floor. The path down them leads to one Missile Tank on the right, and another Missile Tank on the left, both of which have shootable walls blocking them. You can use the X-Ray Scope to figure out the precise location of the paths. The most efficient way to get both Tanks is to try to fall so that you activate both sets of crumbling blocks, then aim diagonally down while falling, making sure to clear the left and right path. If this doesn't work out, then you can simply go back through this path once you fall all the way down. When jumping to get on the paths, try to land on the crack between the long bricks to ensure you activate both sets.
Use a Power Bomb at the bottom to clear the next path, which will deposit you in a familiar area. If you want to keep collecting items, take the bottom path left in the room with green Space Pirates (which you can kill with basic shots due to your beam upgrades) which you've been on before to get back to Brinstar.
Your journey continues in Brinstar.