Samus begins Metroid Zero Mission in the Brinstar region of Planet Zebes.

Get Morph Ball

From where you begin the game, go to the left. Jump up the steps to the left and continue to the left to find a shiny ball sitting on a stone column. Jump onto the ball to collect it. This is the Morph Ball. As the game explains, you activate it by pressing down twice on the control pad. You will morph into a ball and can roll through narrow passages. Use this to roll through the tunnel to the right.

Get Long Beam

Now continue going to the right. Shoot the door to open it. You will pass through a room where a creature is going around and around a line of rocks. Go right again and go through a room where a few creatures will fall down from the ceiling toward you. Don't stand close to these when they land, because they explode after a moment and you will get hurt by the pieces that go flying off.

Use morph ball to go through the tunnel to the right. At the end of the hallway, you will find a Chozo statue with glowing light coming from its hands. Jump onto its hands and roll into a morph ball. The statue will hold you, and you will learn your next objective: a room far above where you are now.

The hallway behind the statue will open, so continue going to the right. Note that the Chozo statue also recharges your health.

There is a save room if you keep going to the right. Exit the save room and make your way up the tall room. Along the way, there is a brown creature called a Ripper that flies back and forth. You can't damage it with your current weapon, so just ignore it and continue going up.

You'll see a door on the right, but even though you can shoot some of the rocks that block the path to it, your beam doesn't go far enough to destroy all the blocks, so just ignore that door for now and keep going up.

Finally, you see a door on the left. This door leads to your destination, so shoot it and go through. Go left until you're at the wall. Crouch and shoot the blocks out of the way, and roll left. Keep going to the left, and open the door at the end. Go through and shoot the egg that the Chozo Statue is holding. Jump onto the object in the statue's hands to get Long Beam. Now you can shoot farther than before.

Learn Your Next Destination

Stand on the statue's hands and press down twice to turn into Morph Ball if you need your energy recharged. Then go through the door on the right.

Go to the right and jump onto the ledge. Crouch and shoot away the rocks, then roll through the tunnel, then jump up through the hole in the ceiling and go to the left. Crouch and roll through the tunnel, then shoot the rocks above the tunnel to get rid of them. Make your way up, shooting rocks in the way, and you'll end up in the upper passageway in the map. Go to the right and a Dessgeega will fall from the ceiling. Keep your distance of it and keep shooting at it until it's destroyed. The door on the right will start flashing. Shoot it and go through.

Stand on the statue and use Morph Ball. Your destination will be added to the map and your health will be restored. Go through the door on the right.

Get Missiles

Make your way down the tall room. Ignore the door on the left. Make your way down to the door on the right. Shoot the rocks so you can use Morph Ball to go through the tunnel. Go through the door on the right.

After a tunnel, you will see a red door on the right. You can't open it with your current weapon. Instead, make your way down the tunnel. The blue door on the right leads to a save room. Exit the save room and go to the bottom of the tall room. Go through the door you find there.

Go to the right, and the room will be shaking, but you can ignore it for now. To the right, you find a Missile tank. Hold R and press B to shoot missiles. You only have 5 right now, but you can recharge them with power-ups that enemies drop on defeat.

Since Missiles open red hatches, go back the way you came. But you will be stopped by an enemy that you have to defeat first.

Deorem, Part 1

Deorem will block the left and right side of the room, then its head will come down from the ceiling. It will sometimes move its head farther down in an attempt to hit you. Sometimes one side of its body will start to shake, shedding spikes that will damage you if they hit you, so stay away. Shoot its eye with missiles when the eye is open. To refill your missiles, you have to shoot the spikes that come off of Deorem.

Eventually, Deorem will go away and you can continue going to the left. Go through the door on the left, then go up the tall room until you reach the red door on the right. Shoot it with a missile to open it, and go through.

Reach Your Destination

Mellows will fly down from above, and Parasites will stick to you. The parasites will go away when you leave the room, so just make your way to the right and go through the door. You will end up in a small room. Go through the door on the right.

In this room, jump up onto the block above where you entered the room, and you will see a Hive to the right. Before you shoot it, jump up to the left ledge and walk left through a hidden tunnel. There is a Hive on the left. Shoot it repeatedly to destroy it, then go left to get a Missile Tank. Then go back to the right to where you saw the first Hive. Shoot it repeatedly to destroy it, then jump to where it was and go to the right, and you'll find another Hive. Destroy it as well, then keep going to the right to find a door. Go through.

You will be in another small room, and Parasites will keep coming down from above, so go through the door on the right to escape from them.

Crouch to shoot the bottom two blocks on the right, and you'll reveal a Missile Tank. Shoot the blocks above it or roll through the tunnel to get the Missiles.

Go to the right, and Deorem will attack again.