Mission 6 - For Bella
Follow your squadmates. The Pulse Rifle is best for this open space.
Eventually you’ll reach the Spitters, who spit acid! Keep your distance, strafe and aim down your sights. As you head down the slope, you’ll soon find a health pack and full armor pick up.
Enter the structure. Hang around during your squadmates’ banter and move through the sliding door O’Neal kicks down.
Any of the shotguns will do you well until you get to the open space with Spitters.
Upon reentering the structure, you’ll be faced with Spitters again. Keep moving.
When you get to the first turret, crouch down to avoid getting hit. Take a left to turn it off.
At the next two turrets, Winters (you) will tell the squad that he’s going to flank the turrets. Run down the hallway and crouch down into the air vent on the left. In the room it leads to, grab the health pack before jumping up the stuff on the left.
Continue down to find the two turrets on your right, one in each room.
Your squadmates will rejoin you. Follow them to the next room.
Make your way around the horseshoe-shaped courtyard, fighting the Weyland-Yutani soldiers along the way.
Keep following your squadmates as you fight both Weyland-Yutani soldiers and Xenos. Be careful not to get too close to explosive barrels, and keep an eye out for the points where Xenos jump in. Since they do so at consistent spots, you can sort of camp at these.
Mission 7 - One Bullet
After the very first skirmish here, run up the stairs (they’re in the open) and past the burning barrel for a full armor pick up.
Follow Bella’s lead into and through the caves.
After the cut-scene where the... ahem... inevitable happens, you’ll go into the Weyland-Yutani labs. The way forward is simple since the whole place is clinical and well lit.
Once you encounter the APC, sneak around it to the left and across the circular battlefield.
Follow O’Neal’s lead, and keep crouched behind crates and stuff. O’Neal will instruct you to destroy the fuel barrels around the APC, though if you just take your time he’ll do this for you.
Next use your Motion Tracker to locate the crane controls once you’ve pushed the APC back (O’Neal will destroy the fuel barrels for you).
In the structure you’ll have to shut down three power cells. Two are on the ground floor and one is above. O’Neal doesn’t lead you in this, so use your Motion Tracker.
Mission 8 - Rampart
Run down the hallway and take a left with O’Neal.
In the next room (where Winter says "Oh, that happened in here), open the first door on your right for armor and an audio log. Then follow O’Neal down the stairs and into the elevator.
Meet the Queen. Once your route gets blocked, turn back and follow O’Neal down the stairs.
Open the big door straight ahead and step into an open battlefield. Use the barrels on your left for cover and try to play the Weyland-Yutani soldiers and Xenos (mostly Spitters) against each other. Grenades are good here because they’ll bunch up in the distance.
Pick up supplies (there should be two health packs, so one can be backtracked to) and move up the hill. You’ll face more Spitters and a few heavy gunners.
During the lull after this second battle, open the two green doors to the structure on your right for supplies. You can also use this structure to get to devastating flanking positions during the fight.
For the third battle, a good strategy is to stay uphill and lob grenades behind the yellow and black concrete. Some Spitters might rush you, but just wait for them with your shotgun out.
Head downhill and pick up the pieces. You might unlock the last weapon of the game’s arsenal now, the Battle Rifle.
Use your Motion Tracker and enter the structure with O’Neal.
You’ll enter an infested tunnel before finding a zig-zagging metal path with plenty of Weyland-Yutani soldiers to greet you. Use the Battle Rifle if you’ve got it (it’s perfect for this situation), and keep pushing ahead. Enemies seem to keep spawning until you overrun their position.
As you move along to the right, explore the small building for an audio log.
In the next zone (After the small building on the left), play defensively with your Battle Rifle until O’Neal shouts "We’re clear!"
Explore the whole platform for supplies before hopping in the elevator.
Next is an infested tunnel with a few Weyland-Yutani soldiers. Keep behind O’Neal and use that Battle Rifle!
The tunnel leads to one of the more memorable images of the original Alien film: the fossilized alien throne thing. Rushing your enemies isn’t a bad idea here. Three Weyland-Yutani soldiers will come at you first, all in a row. Down them with the Battle Rifle and throw a grenade at the next wave.
One more infested tunnel. You know what to do.
The tunnel leads to a tough open battlefield, but there are plenty of supplies to keep you going. Play the Weyland-Yutani soldiers and Xenos against each other, and don’t be shy with those grenades and special ammo.
Run through the structure with O’Neal and take out the three last Weyland-Yutani soldiers of the mission.
Mission 9 - Hope in Hadley’s
Move through the terrain with Cruz and O’Neal, fending off a good dozen Spitters. The Pulse Rifle is one of the better guns for this. Use your squadmates, helping them focus fire or keeping more distant Xenos in check.
Grab the sentry gun as Cruz orders and place it close to the spot of light made by the lamp. Contribute to its fire and (cool trick) grab the gun again when the door opens.
Take a left as soon as you enter the building and explore the farm room for a legendary weapon (Vasquez’ pistol) and full armor pick up.
Move through the door and up the stairs, but LEAVE THE SENTRY GUN BEHIND! You’ll grab it again later.
You’ll have to rescue two marines in this upstairs area. One is behind a door you have to torch open. The other is lying on the ground under burning hardware. Use your Motion Tracker to find them, and keep a shotgun in your right hand.
Head back down the stairs you originally went up to rejoin your squad, and grab the sentry gun.
Place the two sentry guns (the one you’ve been lugging with you and the one you find) in cross-firing positions.
You’ll be swarmed by plenty of Xenos here, but there’s lots of armor, health, and an infinite ammo stash to keep you going. Keep moving around, use your shotgun, and grab ammo when you need.
Grab a gun and head out with your squad as the big "garage" door opens.
You’ll face a big triceratops-like Xeno here. It looks invincible, but it’s not. Immediately place your turret, and shoot the thing up. You’ll see it start to crack and yellow as it takes damage. When it rushes you, sprint in a perpendicular direction to avoid it. If you’re knocked down, immediately sprint once you’re back up. Use your weapons’ secondary fire for extra firepower.
Oh boy, next you’ll have to disconnect three fuel lines from the ship, fighting off some Xenos waves along the way of course. There’s a health pack, full armor pick up, and infinite ammo stash close to the ship.
A good thing to know about the fuel lines: you don’t necessarily have to march onto the raised platforms to disconnect them. Sometimes you can move in behind them, jump up, and hit action.
Between disconnecting the second and third fuel lines, you’ll likely have to fight off some Xenos. The shotgun is good for this.
After disconnecting the third fuel line, you’ll have to resist the remaining Xenos. Just keep your wits about you, stay in open spaces, and look in every direction around you to find enemies.
Mission 10 - Derelict Reclaimed
Take out the heavy gunner and move on.
Cut the door and grab the Incinerator (a flame thrower) inside on the left. You can use the Motion Tracker with the Incinerator equipped, but switching weapons will drop it.
Move through the nest area and burn (or melee) the closed eggs. Getting close to one that’s just opened will have a Facehugger jump onto you and prompt a QTE, so be sure to take them out.
You’ll be moving along multiple groups of eggs. If you’re disoriented after a fight, use the Motion Tracker.
Eventually you’ll move up some stairs to an elevator. Keep exploring the platform to find the power switch. On the way there, a Xeno will ambush you, so have your shotgun ready.
Join your two squadmates in the elevator and hit the switch.
As you move through the infested area and hear the radio chatter, there’s an incinerator on the ground for you to grab.
If you don’t mind another egg nest, you can head down the stairs before leaving the fossilized throne area for a full armor pick up.
Move on and to the open battlefield. Use your Battle Rifle to take out a few Weyland-Yutani soldiers, then rush left to grab the RPG launcher. Two shots will take out the AA gun.
Once you’ve destroyed the AA gun, run into the structure near the elevator (where your teammates are waiting) to grab a health pack, if you need it.
Get in the elevator and hit the switch. Leave the RPG launcher unless you really want it. There are more ahead.
Take out the four or five Xenos rushing up the hill then move down.
Once downhill you’ll join up with new squadmates. The Battle Rifle, again, is a great weapon here, especially against heavy gunners.
Three Weyland-Yutani soldiers will run out of a structure. Take them out and enter where they appeared from for another RPG launcher. Three shots will destroy the AA gun.
Next you’ll come across another Weyland-Yutani soldier vs. Xeno battle. Use the higher ground and your Battle Rifle to whittle them down. Then be sure to shut down the turret before moving on in the direction it’s facing.
Next is the third AA gun. In the same shelter you find the RPG launcher is a legendary weapon (Frost’s flamethrower).
After the fight, use your Motion Tracker to find a rail to jump down from. Keep moving through the few Xenos that surprise you, among which are some Spitters.
Next you’ll find some survivors in an open battlefield. Take out the numerous Xenos here and then run around until the Queen shows up.
The Queen. Your first objective is to survive her presence until air support arrives. Hiding in a shipping container is best.
After the Queen escapes, follow your squad into the structure. Take out the Xenos and loot the shipping containers for supplies.
Move through the shipping junkyard and take out the Xenos as they ambush you.
Next is a Weyland-Yutani vs. Xeno fight. Play it smart!
Rush uphill to complete the mission.
Mission 11 - Home
Here you’ll face the Queen again in a clever boss fight. Avoid the Queen by dashing through the shipping containers. This brings you a safe one that goes all around the Queen’s pen. Lure her to one side before dashing around the other, and through to the middle. As Bishop advises, here you’ll have to hit four manual buttons sequentially. Once you’ve gotten all four, run back to the safe area and behind the central launch pad thing. The Queen should move over to you, at which point hit the switch.