After the lengthy intro, exit the small room through the only door. Go to your right, as the first door you see is locked. Notice that turrets are harmless, and are oddly out of ammo. The group of soldiers that run by will be harmless, and won't notice The Sheps.

You will soon come along a flaming wall hole, a camera, a plug, and a door. Notice that as you approach the camera, the gate will shut until you back away. You will solve this by taking up a small rock, and chucking it at the plug. Jump while you throw to get that extra distance. Once the plug is hit, it will detach, and you'll be free to go along on your journey. Ignore any stairs you see, as they lead to no where.

You will seen come along to a large room, blocked off by a Combine Field. Your first move is to enter into the door on your left, as pictured. Once inside, there are boxes. Take these wooden boxes out of the room, and stack them up at the fencing like so;

Two will do, but three are a safe bet. Climb those boxes to hop the fence, and go on up the newly accessable stairs.

As you enter the new room, turn left. You will see a button. Activating this button will deactivate the field, and allow you to move on. But before you exit this part, you must clear the doorway.

This will lead you to the room where the boxes were originally found. Proceed logically.

You will encounter a field where contact will result in death. It turns on and off with a pattern. two short openings, followed by a relatively long opening. Run through then. Procceed logically until you reach a dead end.

Turn left, and move the boxes to enter the bathrooms. Go straight down the showers, and take a left, your first left.

Moving down along the stalls and toilets, you will reach this fence door. Enter it, and the subsequent door.

Once inside of this room, grab a box and move it to hop up onto the platform. Close the valve. The only valve. Backtrack until you get to the fork again.

Locate and enter this door. The path will now be clear of the steam that used to be the blockade. Continue down the hall until you encounter some red tripwires and a sleeping zombine.

Get close enough to awaken it, and then run back. The zombine will attempt to run towards you, and will instead run into some explosives. It will be dealt with then. Proceed logically into the large, slightly flooded, tripwire room.

To your left is an explosive barrel. Obtain this carefully, and manipulate it to the tripewires on your right.

Stay a safe distance while it explodes, and then proceed down, ducking under the remaining tripwires. Watch out for flying glass.
Continuing along to the end of your platform, hop the rail into the wire while avoiding any tripwires.

Swim over ot the next platform.

Grab a barrel, and proceed to your right. Trip the tripwires with the barrel. Getting a running start for extra distance. Progress logically.

In the next room, move to opposite [locked] door, and obtain crowbar.

Turn around and break the padlock. Raid this room.

Break these boxes, and proceed into the vents. There will be a dropdown inside of the vents. Upon dropping down, you will be greeted with a loading point.

After loading point, proceed logically.

Exiting vent, drop down onto the pipe.

Hop onto the higher pipe, and walk along to the walls. Drop down onto the panels, and tiptoe along.

Going to the edge, the antlions will notice you, and attempt to approach. They will not jump, and you can pick them off with your pistol from above, or hop down and give them the ol' razzle dazzle with the crowbar.

You will proceed onto the floor, and look to the left wall. There will be a large combine field, and a locked door to the right. Turn around, and face the stairs.

Notice and enter the door. Go down the stairs. Beware of barnicles.

You will be greeted with two doors. The one on the left is locked, and the right is unlocked. Enter the right door.

Ahead is a sewer like tunnel. Go along, beware of barnacles, and enter the first door you see.

Once you enter, go no further than absolutely neccessary to fire upon a zombine. Do fire upon this zombine. If you've maintained a safe distance, then you will be out of range for the zombine AI to see you. Pick them off with the USP from your position, or you can move forward and have them go through the field and run towards you.

Once you've gotten rid of the zombine, to the left of the door are supply boxes and a vent. Treat yourself to the supplies, and enter the vent.

Beware of two headcrabs inhabiting the vent. Proceed along.

Looking up eventually will treat you to the tip of a gnome's head, and a beer bottle. Noclipping up rewards you with a peculiar scene.

Continuing on through the vent, you will reach the room. Drop down. If you've eliminated all necrotics and parasitics before entering the vent, the area will be safe, and you've been saved a close quarter combat with zombine.

Entering the more open area, turn to your left, and in front of the panel will be a shotgun. Equip yourself with such.

Going ahead, near the circuit breakers, is an SMG. Equip the weapon for later use.

Look up, and pull the switch which emits sparks. Doing so will turn on electricty, as well as lights, for the entire level.

Turn to your right, and press the button. This button will deactivate the shield keeping you in the room. Backtrack to the large fielded door earlier in the level, and beware of barnacles on your way back.

The large door has opened, and you may open the redundant field from the console.

Enter the elevator, and treat yourself to supplies. Make sure you weapons are fully loaded, and your health is as full as you can get it before you head up by pressing the button.

Take cover, and prepare to learn the first tactic to getting good. Once you are behind this cover, and the doors have opened on the next floor, swiftly strafe to the left, and take a quick shot at the enbunkered combine soldiers.

After taking the shot, quickly return to cover. Doing this quick enough (quick is the key), you'll be able to take minimum damage while getting a definite shot off. This tactic will be useful for later fights.

Once the Combine Soldiers are bested, to the right of the room are supplies. Use these to recover from your battle.

After you're finished patching yourself up, enter this door. Follow the uninhabited halls until you are outside.

Once outside, go up the stairs and turn around, walking down the ledge.

On the ledge are supplies, as well as on the dumpsters. Save these for later, if you can. Return them whenever you need to.

Approach door, and ready weapons by making sure they all have a full clip. Once you open the door, you will be kindly greeted with a flock of antlions. Eliminate them.

Soldiers up on the turrets currently mean no harm to you. You can pick them off from there without danger

In the far right corner is a small control station. At the entrance are supplies for you, and a button within it to shut off the field.

Be wary, as pulling down the shield will flood the courtyard ahead with combine soldiers, and the turret soldiers will be split between firing at you and the antlions if you have not already gotten rid of them.

Carefully aproach the turn, as a combine soldier mounting a turret is down the area.
While crouched, waltz on over to the dumpsters.

Sprint to the laundry cart, and prepare to commit a Schrodinger's Crouch.
A Schrodinger's Crouch is when your hitbox is crouching, while your camera above the hitbox, allowing you to fire upon the combine soldier without ever being hit. To preform this, Crouch down. Release the crouch, and before your camera is standing fully, crouch again. You will be stuck in the camera position while your hitbox is crouching. This is the most important tactic in Prospekt when in a firefight involving similar cover props.
You may remove this combine soldier.

Push forward and enjoy generous supplies. Go through the fences, and complete a guerrilla style offense.

Run a figure eight, peppering the soldiers with SMG bullets, and run through the fire in case you could possibly get a combine soldier to run through the fire as well. Return to the fences, and run through them. Schrodinger Crouch behind the mounted turret's barrier, and face the fence. The combine soldiers are afraid of fences, and they will remain on the other side. The soldiers will be relatively easy to take down if they were properly, and evenly, shot during the guerrilla attack. If there are grenades, take logical evasive action.

After the soldiers are all dead, re-enter the courtyard and head towards the compound.

Inside of the compound is a room.

Restock supplies and prepare weapons.

The button will deactivate the thumpers and the pictured field. Once you've done so, haul ass towards the feild, and turn right once within the fencing.

Once at the end, jump up the cooling units and panels until you encounter a breakable vent. Break the vent and escape into the indoors once again. Proceed logically until the next loading spot.

Proceed logically until you can drop down, and stock up while you can.

Around the corner are two antlions, and just that. The doors on the right just contain dead vortigaunts. They are of no use now. Proceed logically until you've reached the next door.

To the right in the next room is broken glass, and some combine soldiers going up against some antlions. Do not fire a single shot. The antlions will win, and you will never come across the room, so don't shoot as to conserve ammo.

Proceed logically through the next door, but beware, as the door after that contains a room with antlions.

Clear the room, and proceed to the next door.

There are two soldiers and a turret. To combat them, preform the strafe tactic from back in the first part.

After you've taken them down, go back into the other room and grab the computer case from under the table. Position it like so, and use it to block the bullets as you charge at the turret.

Continuing on, you will reach a gate. Beyond the gate are going to be combine soldiers running by. You will fight these soon. For now, you must open the gate with the console button. Walking through the gate, and turning to the right, the soldiers will be oblivious until fired upon. Shoot a single bullet, and then fall all the way back to the combine barriers. Schrodinger Crouch in front of them and take out the soldiers.
After that, the door will now be open. Go through it, and enjoy the pleasent break. 2 minutes, Shep.

After this, you'll be inside of the short range teleport chamber featured in Half Life 2.
Run off to the right.

Stand on the catwalk, and let it fall down, giving you a safe path.

Once on the floor, jump into the portal. When you materialize in the artic base, you must walk towards something to trigger the next event. After a few more locations, you get the loading.

After the last loading screen, you will appear in front of several combine soldiers. They will be eliminated by some electrical arcs. The combine will notice their unresponsivness, then they will attempt to breach the room. This would normally be a large firefight, but is easily skipped. Run to the pictured flight of stairs.

Run along the beams to this vent.

Use your crowbar to break in and skip the entire fight. The music will end shortly, and you will be safe. The vents are uninhabited by any aliens.

In the next room, you will go into the room on the right. Ready shotgun, and fire it against the zombie hiding behind the crates. The crates will most likely be destroyed afterwards.

Use the barrel to enter the vent, and proceed logically.

Do not drop down into the next large room, but instead pick off the headcrabs from your perch, as they can not jump high enough to attack you.

Drop down and proceed logically to the unlocked door.

Stock up on the supplies, and move to the cold water intake door.
Initiate a Schrodinger crouch as high as you can get it before entering, as there are two soldiers manning a console up on the platform. Sneak along unnoticed, and your first shot will most likely be an instant kill due to stealth shots being critical shots. Deal with the remaining soldier.

Proceed logically until the next large space. Trigger some combine soldiers in the next room, and fall back to the last room with the consoles.

Schrodinger crouch behind the side of a console, and fire upon the baited combine soldiers. Sometimes, with luck, they will attempt to melee you without ever hitting you due to the geometry of the console. Draw more combine soldiers back as many times as you need to. Once the room is clear, proceed logically.
The next door simply requires you to initiate the strafe tactic to kill the next soldiers. They will tend to ambush. Throw back grenades by grabbing them like a crate and using attack when you need to. There is no real tactic for this.

The next door will reward you with an SMG grenade, and has two combine soldiers up on the stairs. Initiate attack with the SMG grenade, and use the strafe tactic to take them out.

The next two soldiers will be at the top of the next landing. You can not shoot through the grated floors. Schrodinger crouch and fall back.

Abuse the pictured angle to best the soldier on the right, remember to Schrodinger crouch to keep your hitbox out of the way.

Go back to the base of the stairs as pictured, and Schrodinger crouch to get rid of the next soldier.

Proceed up the stairs, and use the strafe tactic against the next two soldiers.

Schrodinger crouch behind the concrete to combat the next soldiers.

Although, beware of soldiers to the top right as they will attempt to flank you.

Lead them back to the doorway, and use the strafe tactic to remove them.

At this point, the area will be filled with manhacks. Use your crowbar to kill these off, and strafe in circles around them to avoid their attacks.
Proceed logically into the disinfection chamber, and enjoy the loading screen.

Proceed logically after the loading point to the next door. There are no enemies until then. Stock up with the supplies provided, and ready your magnum.
The next tactic is to snipe the soldiers inhabiting the next large room with the magnum, or your most accurate weapon. To achieve maximum accuracy, hold down you zoom key, and hold down your primary attack control. Aim at a soldier's head, and then release the zoom. The shot will be almost instant, and will be much more accurate than a normal crossheirs aiming. Re-enter zoom immedietly. After you've picked of the two or so soldiers, run in a few paces to trigger the rest of the soldiers, and go back to the door. Pick them off. Focus on the combine elite soldiers, as they have a tendancy to rush you. Shut the door when grenades are tossed at you, or just throw them back depending on your skill level.

You may use your next most accurate weapon once your magnum is depleted, preferably for the charging combine elite soldiers.

Once the area is fairly cleared, walk into until you see the far right corner. Manhacks will flood in, and you will fall back to the door. Crowbar them down to preserve ammo. After that, clear out the stray soldiers that may have been left over, and treat yourself to the many supplies and ammo boxes around the room.

Proceed to this building.

Pressing this button will deactivate the currently on field, and will release hunters into the area. This is another firefight.

As with all firefights in this game, there are exploits and shortcuts. With this one, just charge through the newly opened field along the catwalk to the door.

Shutting it behind you will lock the hunters in the room, and keep you safe. Enjoy the supplies in the room and reload all your weapons.

Proceed to the pictured door.

Proceeding logically, the pictured turn will have a trio of soldiers run down. Use the strafe tactic to kill them all.
Proceed logically, and open both of the doors. Make sure both doors are open, and sprint back to the position where you strafed to eliminate the orginal trio of soldiers.

Use the corner to attack the elites again, but beware, as they have an affinity for proximity to you.

Proceed forward again, open both doors, and draw the attention of some of the soldiers in the next room.

Schrodinger Crouch behind the computer desk, and fire upon them from there. Go out of cover and draw more out if you need to.

The next door will have some more soldiers behind it. Open the door and draw them out, fall back to the computer table and Schrodinger Crouch again.

Enter the room once cleared, and press the pictured button. The button will open the door, and proceed logically. No enemies will be there on the way to the next loading point.

Going down the elevator, the right turn will be a group of soldiers. This is when the strafe tactic is the most essential. Use the strafe tactic to kill off the soldiers. The turret will not lock on to you if you are quick enough. Run forward to the next turn, then swiftly fall back to the original position. You will have been pursued by another group of combine soldiers. Use the same tactic in the same position.
The next hall contains another garrison of soldiers. Eliminate them, using the strafe tactic again.

Beware the turret in the corner. Once you've taken that down, press the button and open the door.

The door will open to several turrets, Run to the pictured nook. This new position is a prime area to take down the frontmost turret with your bullets.
Run to the other side of the opening, and then sprint over to the pictured object.

Quickly charge over to the side of the turrets.

You'll be able to take both down from this point.

Proceed to the next closed door, press the button, and fall back to behind the closest cover. Use the strafe tactic against them. After they're all dead, reap the weapons and health, and press the next button.

Take cover behind the column, and strafe the next group to death as usual.

The next room will contain two turrets. If you have any grenades, toss them over at the turrets in attempt to knock at least one over, as the charge will be taxing on your health. Run to the pictured nook.

After in the position, let your sprint power recharge, and then charge at them again, knocking them down when you're behind them.

Proceed to the next elevator, which is the next loading point.
This next part, with the large portal, is devoid of enemies. You are safe to press the button.

After a while, the teleport will fully power on, and you'll be free to walk through it.

The next area is a large chamber, which will soon be flooded with combine soldiers. You must be quick to escape to the next area. First run, and take your first left.

Run along, and follow the catwalk.

Jump atop the consoles, and get onto the thin bars.
Run along the bars to the other side of the room.

Jump into this little cavity to escape the bullets and soldiers. Proceed logically.

The beam will turn on and off, keep crouched while inside of the area. Jump and crawl through the emitting hole to get into the next area. Proceed logically.

You will soon enounter walls of deadly energy. Each one of these turn on and off, the first having the longest off time, and the last having the shortest. Timing is all that is required.

Once you've passed the obstacle, jump up the bars to the vent, and crawl through it.

You will come across some floor energy. Walk within the spaces, but beware, as the beams are ever so slightly slower than your walking speed, so tap the forward key.

After you've finished it, progress logically until you reach the holes with combine balls shooting up. While you enjoy what can loosely be considered a cutscene, simply drop down the holes onto the next level between balls.

Once you're at the bottom level, jump and crawl into the pictured vent.
Cue next chapter.

After you emerge from the vent, you'll reach a fork of three paths. All of them meet back together after a few paces, and have no different effects. Proceed logically into the next vent.

When you emerge, you only have a short amount of time before a group of combine soldiers come through. They will not notice you if they're left alone, although you can launch an SMG grenade at their tight group right as they enter if you've conserved your grenades.
You can stay as far back as you need to, just as long as you can still see the ground. Due to the nature of the ceiling, it is impossible to complete a Schrodinger Crouch. Simply pepper them with your preferred weapon. They will go down relatively easily if they were hit with an SMG grenade as they entered. Once they're eliminated, drop down, and go straight through the door. Go straight to the next door, as the first path to your left is locked by a combine field. If you have a combine ball in your pulse rifle, fire it into the room. As soon as the combine are triggered, combine ball used or not, sprint back into the first room. Unholster your shotgun, and turn back around.

Make sure the door is fully shut, and when the first runs to you, quickly walk forward, trigger the door opening, and do a double shot at the soldier as close as possible. Do this with the rest of the enemies. There is no real tactic aside from that.

Return to the room the second group of combine soldiers came from, and press the button.

The previously mentioned field will be deactivated, and you may proceed logically.

When you come to the next large room, the first door on your right is the only unlocked one. Enter the elevator, and ready all weapons. Preferably a shotgun.

After the elevator ride is finished, go through the door, and walk in just far enough to trigger the combine. After you've done so, run back into the elevator, and stay far enough from the door to keep it shut. Pepper the soldiers with buckshot by approaching and back away from it to shut. Do several runs of this, eventually picking away at all the soldiers.

Enter in, and equip the explosives. Keep the rocket launcher out, as it's essential for the next part.

Walk into the next chamber enough to trigger the combine soldiers in there, and run back. They will group together to follow you through both doors. Once they're tightly packed into the hallways preceeding the next large room, you will use the rockets to fire into the center of the pack. Feel free to use as many rockets as you want, since you will have a lot, and will not use them for the rest of the chapter.

After you've cleared out all the combine soldiers, enter the large room again, and enter the elevator.
Ascend to the next chapter.

After the elevator ride, you will begin the fairly short chapter. Proceeding logically, you will come along some health stations. Treat yourself, and proceed logically.

Proceed until you come to the double doors, where behind are two combine soldiers in sight, and one out of sight. If you were impatient, and had enough health, you can rush to the nearby button and enter the portal platform, though, preferrably, you'll walk in, trigger the soldiers, and run back to the last door you entered.

Usse the corner as a part of the strafe tactic. The strafe tactic is good for avoiding the commonality of grenades.

If a grenade is fired, simply run behind the doors, and have the doors block the blast. The soldiers ahead are together just well enough for a well placed combine ball to take the majority out, so use one if you have one.

After you've exterminated the soldiers, proceed logically into the next open room. Obtain health and armor if you need it, and press the button.

Once the button is pressed, step onto the platform.

You will be transported to Xen, and be greeted with familiar surroundings if you played the original half life games.

You may recognize the blue glow pool. It will regenerate your health in 10 hp increments. Proceed logically.

The next large area will contain combine soldiers. Use the low gravity to your advantage to fly around the area, firing upon the soldiers as you pass overhead.

Use the roofs of the buildings to keep a pleasent altitude above the soldiers, hoping back and forth.
After they're all dead, proceed logically to the floating islands, and descend them to the next large island.

Once you land, Schrodinger crouch by the building's window to fire into the building at the soldiers.

You will activate the button, and step back onto the platform. Await transportation and proceed logically to the next level.

As you get back to the orbital sector, you will proceed logically. This will most likely be the hardest level, due to many firefights.

Going far enough, you'll be caught inside of a confiscation field. Your weapons will be ripped from you, and you'll be ambushed by soldiers. This is just a custcene, and you'll simply be transported to a prison cell.

After the screen fades to from black, you'll be inside of a small prison cell blocked off by a combine field. Have patience, as eventually an alarm will sound, and the soldiers will rush out. Later after that, the fields will all go down, and you'll be free to go.

Upon exiting the room, you will find your weapons strewn across two tables. You may reclaim that, and proceed forward to the next large chamger.

In the chamber, make your way to a large console, and press the button. This will activate a promethean-esque hologram in the middle of the room.

Approach the hologram, and stand with in.

Eventually, cameras will deploy down from the ceiling and sound an alarm.

Notice the suit batteries on the consoles around the room. Stock up in the few seconds you have before running to the door from which you entered the room.

This is the first time based firefight in the game, so you must rough it out. The easiest tactic for this, due to the lack of barriers to Schrodinger crouch behind, is to hide behind the sliding door. Soldiers mostly come in ones at you and your door. Remove your shotgun, and when one approaches, charge towards the soldier as it's near the door, fire a double shot point-blank range in the head, effectively 'crowning' the soldier. SMG combine soldiers will take one point-blank double shot, shotgun soldiers take two double shots. Elites take more once they're introduced later in the fight. Reap the health packs and ammo from the fallen enemies, and quicksave (defaulted to be F6) very often.

After the soldiers stop coming, emerge into the chamber again. One of the doors will be sparking, marking that it is enterable. Do so. Beware of stray soldiers.

Proceed logically. Treat yourself to health and armor.
Eventually, you'll come to another door leading to a larger chamber. Stay behind that door, and use any weapon to peek in and out to fire at the soldiers inside of the chamber. Use your magnum+zoom combination to get rid of the combine elite soldiers. They will not charge at you like the others. Note the health and shield. Charge up as much as you can, as another firefight is coming.

Press the button to open the large shutters to reveal your true location, orbiting Earth. Turn around and run for the stairs to the lower level.

Duck and crawl under the stairs.

Due to the style of the steps, there is a limited angle from which combine soldiers will be able to fire at you. You will draw some down to the level, and fire from behind the stairs. Due to the nature of the stairs, and the inaccuracy of combine soldiers, you will remain relatively safe. Grenades will be tossed in from time to time, simply run or throw them back depending on your skill. From time to time, you will have to peek out and get the attention of some soldiers.

After the soldiers stop coming in, you will come out from under the stairs. One of the doors will be stuck open, and you will enter it. It is an elevator. The doors will shut and you will be treated to some rewarding dialogue as you cool down. Make sure all your weapons have a full clip.

After the elevator has stopped, you will be greeted with a room filled with more soldiers. Use the strafe tactic in combination with peeking in and out of the sliding doors to get rid of the soldiers in the room.

After they're all gone, enter the room and treat yourself to some health and armor.

Proceed logically through the next door until you've gotten the attention of the next pocket of soldiers. After that, run back to the entrance of that level.

Schrodinger crouch behind the console in the far corner, and fire off at the soldiers as they come in. Keep going further and further into the level, bringing out all of the combine soldiers to be exterminated.

Once all the soldiers are killed, then you will be rewarded with a large stock of weapons. Enjoy. Once you're all stocked up, turn around.

Notice the button and the door.

Take cover, and activate the button. The door will open, and you will use the strafe tactic to take out the soldiers inhabiting the next room.

After you're done, use the rocket launcher to get rid of the turret. Don't hit it directly, as you will want the turret head to be up.

Open up the next door, and Schrodinger crouch behind the deactivated turret and fire at the soldiers. If the turret is not up, then simply use the strafe tactic and some cover. Fire any kind of explosive at the turret, whether it dies up or not.

Proceed logically and press the button on the console to deactivate the annoying alarm.

Enjoy health and armor, and proceed logically to the next chapter.

Chapter Eight starts off the level with a long elevator ride. After this ride has concluded, immedietly run to the side of one of the consoles, and initate a Schrodinger Crouch. Take out the soldiers from the position, preferably with a pistol, as they will be incapable of damaging you as usual.

Afterwards, you will push on, keep in the Schrodinger Crouch and attempt to fire through the pictured angle. If unable, stay in the crouch. The crouch makes you almost invincible, as the soldiers attempt to target your camera, missing your hitbox completely.

After clearing out the area, enter the Elevator, and proceed logically.

Once the ride is over, the next room is filled with more soldiers. Peek in and out of the sliding door to pick them all off.

Afterwards, proceed logically, treating yourself with the health and armor.

The next area will have three combine elite soldiers to the right. Trigger them, and fall back to the door.

Peek in and out at them, picking them off. They tend to not charge in past the door. Schrodinger Crouch to ensure maximum safety.

After they're all gone, proceed on. Enter the room that the elite soldiers were in, and press the button. That will activate the gunship shipping through the portal.

You'll see some elites attempt to run at you, and then run back. The portal will fizzle them away after a while.

Proceed through the newly opened door.

The room-wide triggerdeath is triggered when the pictured gunship enters the portal.

Haul ass to the next door on your left in the new chamber, don't waste any time.

Entering in, and going forward, the hall to your left will soon have a couple of soldiers coming out. When you've triggered this, run back.

Schrodinger crouch at the side of the console, and fire upon the solders from there.

Proceed logically and press the pictured button. The doorway will have health and armor on either side of it. Proceed back to the large portal chamber.

Run across the chamber to the other door, make sure not to get caught in the portal's energy when it fires off.
Once you're inside and safe, initiate a Schrodinger crouch, and just push forward. Nearly all bullets will miss you as the soldiers aim for your camera instead of hitbox.

Proceed logically to the next button, and activate it. Afterwards, proceed back to the room that first lead into the portal chamber.

To the right as you re-enter, is health and a button. Press this button, and enter the elevator.

Wait for the elevator to shut and go up, and enter chapter nine.

The level starts off with a long walk, devoid of any enemies.

Enjoy health and armor on the way to your next battle.

Eventually you will come to a large room. There are solely combine elite soldiers in the room, so beware.

Sprint over to the side of a console, and Schrodinger crouch. There are around 6 soldiers in total in the main room.

After they're all dead, the goal of the room is to unlock both sides of the large pictured door.

Simply head into the hall to your right when you first walk into the room.

Walk into the sliding door, and proceed logically. There are a few combine elite soldiers. Schrodinger crouch as high as you can, and just push forward, killing them all. Watch out, as they're on an angle, and will have a higher chance to accidentally hit your hitbox.

Once you've finished with all of them, press the pictured button, and one side of the door will be unlocked.

Return to the large room, and head over to the opposing hall.

Treat yourself to health and armor.

Proceed again with either the strafe tactic, or charge in within a Schrodinger crouch.

Once all the combine elite soldiers are dead, press the button to fully unlock the door.

Backtrack to the door again, and deactivate the redundant field.

Enter in, and trigger a loading screen. Hide inside of one of the ridges, because when the door opens, there will be enemies and a combine elite soldier mounted on a turret.

Simply Schrodinger crouch as high as you can, and push forward, evading every bullet and firing your own at the soldiers.

You will be treated with a great amount of ammo and health. Reap.

Proceed to the next door, and enter the elevator.

Walk forward into the core. This will be effectively the easiest firefight in the game.

Simply jump behind the console dead ahead of you, and initiate a Schrodinger crouch, and press the button on the console.

Three combine soldiers will come from the right door, one combine elite soldier, and two regular combine soldiers. Focus on the combine elite soldier, as that one will the be one to attempt to undo your button press.

After all three of them are dead, come out from behind the console and make your way to the next one. Schrodinger crouch behind that console, press the button. Combine soldiers will come out dead ahead, same amount and kinds as last time. Focus again on the combine elite soldier, as it will still attempt to undo your button press.

Come out from behind the console, and go to the next console, on the opposite side from the one you were just at. Press the button, and fire at the new soldier coming out again.

Come out from behind the console, and go to the last one. This is arguably the hardest part of the level. Press the button.

From the right will come the new soldiers. They will have a clear shot at you, so take out the elite soldier first, and the rest of them quickly.

After a while, the core will completely overload, and you'll be teleported out. Enjoy the cutscene.