The Foxhole

A Note On This Walkthrough...
Half the fun of Invasion comes from the surprises that lay in store for you, so I’m not going to go into exhaustive detail here. Even if an ambush, for example, does go badly for you, it’s a simple enough matter to reload and give it another go. But if that ambush proves troubling even when you know it’s coming… that’s where this guide comes in. I’m here to advise you when you truly need the advice.

Before You Begin…
While Invasion features the option to translate the in-game subtitles into four different languages, the main menu is still mostly in French. While you should be able to figure out those that have HL counterparts, the new features will probably stump you until they come up during the game. Here are the new controls translated into English:
  

 
*Note: In order to use this feature, you must hold down the button. Use your mouse to select which areas you wish to apply the battery to, then click the + at the bottom to use the HEV battery. Since the regular use of an HEV battery automatically heals the weakest areas first, the only real reason to heal your suit by zone is if you want to neglect one area in favor of another.
  

Part 1
Once gameplay begins, make your way to the test chamber. Squeeze into the corner opposite the door and sit tight, otherwise the cleaners will pepper you with bullets and grenades when they show up. You’ll also be safe here when one of the grunts blasts the door open for you. Quickly leave the room and round the corner lest the flurry of grenades and eventual cave-in kill you.

Head back the way you came. When you come to the elevator, use your melee tool to break not just the glass but the horizontal bars of the doorframe as well.

When you reach the catwalks with windows for walls, do not try to get past the sentry guns. The designers don't want you to go this way—not only are the sentries invulnerable, but you'll be gibbed if you try to run past them. What you want to do is jump from one catwalk to the next.
  

Because the first keypad code is spoken and not written down where you can refer back to it, you may forget it if you're not paying attention. The code is 8533.
  

When you reach the room with the grunt that blows up the canister, you'll want to climb up the broken vent. However, you don't want to keep going forward (you won't fit, anyway) but turn around and head through the vent behind you.

When the scientist calls to tell you to keep traveling through the vents, you'll have to smash the grate on the side and hop out. There is an adjacent vent into which you must now crawl. While the fan will slow your progress, you should still be able to reach a perpendicular shaft that will eventually lead you to a switch to shut down the fans. Then return to the original shaft (where the scientist radioed you) and proceed on.

Part 2
Use the turret to blow open the hangar door, and if you like, the helicopter as well. If that’s too difficult, run outside and hang an immediate left. When you reach the helipad, quickly open the large door and duck inside. You'll probably want to close the door behind you for protection from the chopper. Next, clear out all the crates in the room. One of these not only holds the rocket launcher, but also hides a vent that will lead you into the security room (and the switch you'll need to move on). Use the rocket launcher to take the helicopter out (if you haven’t already), keeping in mind that you must keep the target painted even after firing in order for the rocket to track its target.

Once you reach the manned tank, you're in for some hurting. Use the rocks and small buildings as cover, moving between each shot the tank takes, and make your way over to the large building. Quickly gather ammo for your rocket launcher and move back behind cover. Wait until a pause in the firing before stepping out to dumb fire a rocket at the tank. Do this a few times until it blows up. To proceed onward, do not jump into the water below the tank. Stick to the walls, scurry up the rocks, and head through the open pipe.
  

Once you're in the water and have reached the broken ladder, you can proceed through two methods. For the one the designers intended, head up the left ladder as far as you can, then turn around and hop out onto the ledge. Switch to the other ladder and repeat the process. There is, however, a trick you can use. Climb onto the left ladder and move as far left as you can. Adjust your view so you are looking slightly up and to the right. Then move both forwards and to the left. You should successfully clear the gap in the ladder.

When you reach the area with the infrared/night vision pistol, don't worry about using it yet. The enemies in this area all have flashlights, so it's easier to just aim at the light sources. Clear the entire area out before activating the elevator. Notice the progress bar, and how there is a black line. That line indicates where the elevator intersects with the level you're on. You're going to have to run all the way from the controls to the elevator to arrive there in time. After this area, it will be a good idea from now on to use the infrared mode to scan around corners and into rooms.

The first rocket grunt in the game is coming up, and they’re tough nuts to crack. Stay clear of any walls, and strafe back and forth to dodge his rockets. Since cluster bombs explode on impact, try to hit him square in the face with one. The clusters should finish him off. Generally, I’ve found this to be the most effective method for them.

In the room with the tripmines and crates, it's best to chuck a grenade in and get as far away as possible. Even with the door closed, you can take damage from the large explosion. Only two of the crates in that room are indestructible. Use them to crawl through a skylight, and then head towards the rocky area above.

When you're in the hangar under the grate, you can get out by opening the corner sections. The code you need is once again spoken out loud: it's 4274. Once outside, your objective is to climb the radio tower and use the airstrike controls to blow open the tunnel (left side of the mini-map).
  

In order to dodge the tanker explosion, run quickly down the side tunnel to the toolbox. Next to it is an open manhole, into which you should drop. In the next area you'll have to turn on all six vents and flood the three areas indicated on the mini-map. Just proceed from room to room, making sure to hit the switches in each. You’ll notice that in one of the rooms (indicated below), there are a few out of the way supplies. Here are a couple of ways to get to them:
  

Once you reach what remains of the area in which the tanker exploded, don't use your infrared pistol. It's best used at short range. Here, just aim for the flashlights again. Note that at the end of this section, there are a few sandbag barriers. There is a rocket grunt here, and he does not have a flashlight. Try to catch him by surprise instead of the other way round. To proceed, there is a small tunnel at the right side of the rubble blocking the end of the tunnel. In the next area, just make sure you topple the tower.

Part 3
Once part three begins, rush past the two rocket grunts, head down below, and break the boards to slip inside. For this area, I strongly recommend a good deal of quicksaving. Take out a sniper, then save and move on to the next one. The best way to take out snipers is to equip the sniper rifle, zoom in, and slowly sidestep until you can see just their elbow. Shoot them, and they'll go down with one hit. Also use your infrared pistol to spy on nearby enemy positions, and remember that you can shoot through walls.
  

After wading your way through all the snipers, you'll reach an area with glass elevators. This is the "stealth area" of the game, and you'll have to avoid being seen by security cameras. If you are seen, load a save before you were. You are not allowed to progress once the alarm goes off, no matter what you do. To avoid the first few cameras, break out a window when the elevator reaches its stop, and make your way along the ledge outside until you’re forced back inside. Do the same for the second elevator. 

Stick to the walls to dodge the cameras in the next several areas. It will be obvious when you should duck through a side room or simply slip underneath a camera. Save often. 

You'll eventually reach a room that has a Xen aquarium. Use the crate in the room to climb up on the shelf, and then make your way along, smashing out all the vents. Don't go in the water yet—it's toxic. Now return to the controls, drain the tank, and quickly make your way back through the vents and past the aquarium.

Make sure you check the computers (use them) as you continue to sneak along. One of them will show you the password needed to shut down the security cameras. Note that you'll first have to enter the computer systems and look around to find what you're looking for. They'll be in French, but it's simple enough to figure out.
  

After you've been scanned in the security booth, you'll find yourself in an area with blue walls. What you're going to do here involves activating several different machines, which is simply a matter of pressing the right switch. Just know that for one of them you have to first load the device in question, and then use it a second time to activate it.

After you've got your new energy minigun, you'll be rushed by two rocket grunts. The minigun isn't a particularly great weapon, but it does have a useful, shotgun-style secondary mode. Rush the rocket grunts and hit them with a full blast each to take them out of the picture.

When you reach the stairwell with destructible steps, take out the one grunt that is shooting at you but don't advance. Grunts can see you through the steps, unfortunately, and will tear you to shreds. Even the odds by tossing a cluster bomb into the stairwell. In the very least you'll destroy most if not all of the steps, and if you're really lucky you'll take out all the grunts in the process.

After the cutscene, your first priority is to cluster bomb the rocket grunt that comes in the way the GMan went out. Then take care of the rest of the grunts, adjusting your position based on where the Apache is. The Apache should be the last thing you try to take out. Because you're shooting at it through the skylight, don't worry about getting a target lock (though it is possible) and just dumb fire your rockets until it falls.

In the next area, hang back in the doorway and drop the Apache with rockets. If need be, charge forward to the crates, which contain both health and rockets. Be aware that grunts will take potshots at you from the building to your left, so take care of them before you make a run for it.
  

Once everyone's dead, climb atop the helipad and equip the sniper rifle. Zoom in on the distant building and take out the sniper you see therein. You'll want to save at least one bullet for another sniper that you can't see yet. If need be, line up the remaining grunts with your sniper rifle, then switch to a pistol and drop them with it instead.
  

In order to jump the fence, you'll first have to destroy one of the towers if it hasn't been already, which will make you a bridge. Then crouch-jump from the helipad itself (not the building on which the helipad is sitting) onto the corner building and use the fallen tower as a walkway. The sniper you've been saving a bullet for is up and to your left. Proceed with caution.

Once you've reached the large vertical vent, first take care of the single grunt below the fan (watch out for the scripted rockets, they can hurt you if they hit the blades). In order to safely get past the fan, crouch and drop down so the blade pushes you safely onto the top of the pipe. Stay crouching and move slowly forward to land on the lip of the pipe.

From there, you're going to run forward and duck while in the air. You should safely land inside the next opening down. Immediately turn around and jump to the next pipe. You’ll just miss the falling fan, and will now be positioned behind a trio of grunts as they rappel down.

After your next jump you’ll hear an elevator. Start unloading into the wall opposite you and you'll take out the hidden sentries before they know you're there. A contact explosive such as a cluster grenade may be needed to blow the wall open. Continue down in the same manner as before.

When you reach the end of the tunnel don't try to tangle with the Apache. Duck down the hall to your right and activate the fan controls. Head back around the corner so you don't take any damage when the chopper blows. From there, jump across to the ladder and head downward to the open vent, jumping from ledge to ledge.

In the next area you'll come across modified assassins. They're invisible when they're motionless, but you can still see their muzzle flashes. I recommend an aggressive approach, just charging towards every flash you see with guns blazing. Once the area is clear of threats, you'll have to blow up some barrels to find a somewhat hidden passage.

After the scientist directs you on what course of action to take, make your way back. Be aware that a sniper is now atop one of the containers, so take care of him before he takes care of you.
  

You don't need to use the tank to take control, just walk right into it. Pay attention to which turret is firing, and take that into account when lining up your shots. Your only real concerns now are explosives. If you're fighting with a tank or missile turret, aim specifically for the part that is shooting at you, as opposed to the chassis or tower. Save often, and try each group of enemies a few times until the damage remains at an acceptable level. Blow up anything and everything, as there are some portions of the game where you can't progress until you've blow a hole in something. When you reach the minefields, take it slow. One mine can destroy the tank regardless of its current damage. Lastly, save before you exit the tank at any time. Chances are there may be a sniper you've missed.
  

Once you've reached the second, smaller minefield, you're going to have to gain access to the underground control room to move on. The key code for this room, however, is neither spoken nor on a computer, but on a piece of paper. Keep an eye out for it, and use it to read the code.
 

In order to gain access to the baby-nuke, you can either find the keycode for the door, which is written on another piece of paper, or jump through the window by the broken catwalk. Don't worry; you can pass through the texture for the metal grating. The baby-nuke, while tempting to try out, is only to be used to clear the rubble blocking the tunnel.
  

Eventually you’ll reach what I call the Nine-Button Puzzle, which consists of a 3x3 grid of buttons. For reference purposes, let's call the top row 1-3, the middle 4-6, and the bottom 7-9. It seems the solution is randomly set to one of several options, though so far both 7-1-9 and 3-1 have worked for me in different play throughs (I’ve also heard 3-4-1 is a possible solution). Your objective is to light up all nine buttons, and if one of these doesn’t do the trick for you, here is a rundown of what effect each button has:
  

Part 4
Once you've reached the sanded-in building, enter through a vent on the roof. Stay up in the ceiling, and look for another vent above you to get where you’re going.

When you reach the red-tinted room with catwalks circling a large container, take care of the one grunt that is shooting at you. Now, instead of circling round and being chewed to bits by grunts firing at you through the grating, hop down to the left where the first grunt was. There should be a ladder to your right headed down to the next level. Take that down, and then once again loop around behind and drop down to the next level. Once you can't go any further down, take out your infrared pistol and take the guards by surprise.
  

To solve the conveyor belt puzzle, move to the top level and take one and only one of the explosive crates. Push it onto the elevator. Now you'll need to head back to the control panel. Activate the controls and change both belts three and four. Go to the elevator and push the crate out onto the belt. You needn't worry about losing the crate; even though it disappears down a tunnel, it's a dead end. Simply go back to the controls and change belts one, two, and four, and head down the same tunnel that the crate goes.

Once you're in the water, you'll have a hard time getting out with the sniper there. My recommendation is to unload a rapid-fire weapon into the area above the ladder. Hopefully you'll take out the sniper, and can then mop up the grunts below. To solve the puzzle where the sniper was, use the lever and then push the crate in the way so it can't revert to its original position.

Behind the goo-covered vent you'll meet the first of what I call flying defibrillators (fibs for short). In this situation, just take out your tool, smash the goo apart, and don't let up until the fibs are dead. In any other situation, it's best to fight them indirectly, usually lobbing a grenade around a corner and taking out a whole group before they know you're there. Otherwise, pull out an automatic weapon and gun them down before they can close distance with you.

When you reach the room with the Gargantua, leave him be while he takes care of the grunts. Pass the time by collecting all the items in the crates and calling the elevator up to you. Once you two are alone, take the elevator down and haul down the tunnel. Duck into the enormous fan (avoid the blades) and stand back. A scripted scene should occur, killing the Garg (who's otherwise indestructible) and giving you his arm as a flamethrower (those squirmy little eggs are the ammo). If the scripted scene doesn't occur, reload before you made your mad dash and try it again.

In the gas-filled area, pick up the gas mask to stop taking damage and only use the tool to fight with. Even the lighter will blow everything sky high. You need to shut down two leaks—one on the ground floor and one on level two, which will require a spot of jumping—before it’s safe to use firearms again. After you've shut them down, pull out your infrared pistol so you can see where all the new Xenizens have teleported in.
  

In the area with the other new Xenizen, the code for the door is clearly written out on a piece of paper. To take out the new flying critter (henceforth a flitter), either use your infrared pistol to shoot it through the corners while it's blissfully unaware of your presence, or rush in and light it on fire with the Garg arm.
  

Part 5
Once part five begins, I guarantee you'll suffer greatly during the freefall segment. The only advice I can give is to quicksave before each encounter, reloading if it doesn't go well. I personally rely on the Beretta to take out the controllers, while the flitters get a face full of sniper rifle. Once the next level loads, move towards the middle of the tunnel. It's possible to clip the outer ledge while you're falling and kill yourself.

In fact, throughout the entire pseudo-Xen section you'll have to do a lot of quicksaving. Don't advance unless you're in great shape, because it doesn't get much better as you go along. Definitely don't keep going if you've no armor and under 10 health. There are some segments where it's nearly next to impossible to avoid damage simply from dropping from ledge to ledge.

The fibs differ somewhat in the pseudo-Xen maps in that in most cases they aren't attacking in swarms but one after another. Because they move in a straight line, just stay still and gun them down as each comes. If you have to move, try moving only in a straight line forward or backwards so as not to ruin your shot.

When you find the last baby-nuke, don't use it immediately. Time it so the cave-in crushes the two approaching flitters. Just make sure you stand far enough back that the shockwave doesn't take you out too.

For the final puzzle, you have to direct each elemental beam into the proper receptacle. Use the device in the middle to see which beam aligns with which element, then pass into each receptacle and listen closely to what you hear. The ambient noise within each receptacle will match one of each element. Then shut off the device, realign the mirrors, and turn it back on to beat the game.
 

^{Note: Originally posted at Hangar16.com on 10/13/03}