Crysis Warhead Walkthrough

Guide written by Andy Yen

Crysis Warhead from GamesPress

Introduction

Most of the enemies, weapons, and suit abilities have remain unchanged from Crysis. This guide will detail the changes specific to Crysis Warhead. For information on previous content, check out the original Crysis walkthrough.

General Strategies

Use your nanosuit! All four modes of the nanosuit are useful for different situations. You should be switching between several modes during battle as the situation dictates itself.
If you are not specifically using any other suit ability, keep strength mode activated for firefights. Your weapons will be more accurate and do more damage to the enemy.
Between battles, don't forget to switch to speed mode to make getting from place to pace faster.
Find cover during battles. Your energy and health regenerates fairly quickly. Even if you are heavily damaged, a few seconds under cover may be enough to survive a firefight.
Try have both a long-range and short range main weapon equipped at all times. The shotgun combined with the Gauss Rifle will be your loadout of choice for most of the game.
The Gauss Rifle is the best weapon to fight the aliens with. One shot will take out drones and 3-4 will take out the larger Scouts.
Remember to customize your guns! Use a reflex or combat sight if they are available. They will make aiming while zoomed-in much easier.

Weapons

KLOB Micro-SMG - These will replace your pistols as your sidearms. They become very inaccurate at medium to long ranges, so the enemy will have to be close to you. They do decent damage and have a high rate of fire. If you don't have a shotgun, these will be your weapon of choice for short range battles. You are able to dual wield these as well.
Anti-Tank Mine - Works as advertised. Pull them out if you see KPA vehicles driving towards you. Try to be cloaked while you do this if possible. They will most likely explode in a fiery mess.
Nanodisruptor Grenade - These grenades are only useful for stunning enemy nanosoldiers. It will fry their suits, making them more vulnerable for a short while.
FGL-40 - This fully-automatic grenade launcher is a wonderful toy to play with. It has two modes of fire, EMP and fragmentation. Most of the time you will be using the fragmentation mode as it does a lot of damage. If you are facing enemy nanosoldiers, switch to EMP to fry their suits.
PAX - You will get this supercharged plasma weapon before the final boss. It has unlimited ammunition, but reloads slowly and has short range. Nevertheless, it will be invaluable in the final battle.

Enemies

Shield-Generating Drones - These look like normal Alien Drones, except they will usually be part of a pack. They have green lines emanating from them, protecting their fellow drones with a shield. You will want to kill these first, as you cannot damage the other aliens while they are still alive.
Orange Scout - These large squid-like creatures look much like their normal blue counterparts. However, instead of dropping alien drones for you to deal with they will drop orange bouncy mines. They will also fire an orange laser beam at you too.

Call Me Ishmael

After the cutscenes, get off the transport and walk forward to get your bearings.
Continue following the soldiers up ahead along the creek. Crouch under the rock outcropping when instructed to. Jump over the log in the creek. When you arrive at a larger barrier, switch to strength mode on your nanosuit and jump over it.
After the next cutscene you'll be given your next objective.
Follow the road, curving to the left. Don't worry about the radio chatter you here, there are no enemies yet.
When you get to the first bridge, you'll see a KPA truck crash into the river. Switch to your cloak and sneak up behind the soldiers. Dispose of them as you wish, then continue walking along the road.
Tip: You may want to pick up an FY71 from a dead soldier. Walk up to one and press F to pick it up. Ammo will be plentiful for this gun as most KPA soldiers will drop their guns when killed.
Two more soldiers will ambush you from the foliage. Kill them and then switch to your speed mode to run towards the objective. Switch to strength mode to jump over the broken bridge when you have to.
After you watch the fireworks, continue walking towards the beach. An enemy jeep will drive towards you. Quickly switch to cloak and walk to the left. You'll see three KPA soldiers sauntering down the path. Get behind them and grab one with the F key. Use him as a human shield and take out the other two soldiers quickly. Time to deal with the jeep. Wait for your cloak to recharge, then drop down to the shacks. Make your way near the jeep without being spotted and toss a couple of grenades at it to blow it up. Get in the other vacant jeep by pressing F. Continue driving down towards the beach.
Tip: Pressing G will throw a grenade.
Enemies will attack you from both sides of the road when you get to the Lagoon resort. Feel free to dispatch them by a combination of running them over and using the jeep's machinegun turret.
When the area is clear, go to the trailer marked by a yellow dot on your radar. Walk to the back and press F to use the laptop to gather intel. After the briefing, you'll get a new target to take out.
Walk back outside and get in the armored APC. Continue driving on the road towards your objectives.
Take a short detour to your left to blow up the propaganda machine for your second secondary objective. The trailer is located near a little bay. There are 4 enemy soldiers here. Kill them with any method of your choosing. We opted to mow them down with our APC's turret. Watch out, as one of them may get up on a fixed-place gun.
Go inside the shack and grab all of the ammo and explosive charges. Throw an explosive charge next to the trailer. Walk away and put some distance between you and it. Switch to the detonator by pressing Mouse 2. Blow up the trailer by pressing Mouse 1.
Get back in your car and head towards the main objective.
Eventually you'll reach a roadblock. KPA soldiers will attack you from both sides here. Kill as many as you can with your vehicle's turret. Get out of your car and mop up any surviving soldiers. Walk in the direction of the green objective marker. You'll see a bunch of rocks blocking the path, but that's easily bypassed by strength jumping.
Get ready for a large battle. Switch to strength mode and watch for a KPA jeep to drive straight at you. Throw a couple of grenades to blow it up and continue down the road for a little bit. You'll want to turn left and make it down to the beach as soon as possible. If you keep walking straight down the road, you'll hit a KPA tank which you can't damage right now.
There are probably a dozen or so KPA soldiers around the beach. Take cover and kill the ones you can. Your goal is to reach the circular bar/restaurant close to the water.
When the enemies are all dead, pick up all the goodies in the restaurant. You'll find some sub machinguns you can dual wield, along with a missile launcher. Take the missile launcher and go find that tank that's been harassing you. Three missiles should take it down and end the mission.

Shore Leave

Drop down to the jungle floor after the cutscenes. You'll immediately be thrust into a large firefight.
Switch to cloak and head to the left side of the jungle. If you're lucky, you'll catch a squad of 3 KPA soldiers unawares. Kill them all and be sure to take one of their shotguns. Drop whichever assault rifle you have less ammo for.
Keep creeping around the foliage, ambushing KPA soldiers. The shotgun will be a one hit kill if you get close enough. Don't worry if you get spotted, switch to speed mode and run at the soldiers to kill them with your shotgun quickly. There are about a dozen soldiers to kill.
Tip: If you need some ammo, there's a small box to the right side of the area, along with some smoke grenades.
Tip: Pressing H will cycle between the different grenade types you are carrying.
When the coast is clear, head towards the large rock arch formation for a checkpoint. There's also a SMG and some ammo in a box right in front of the arch.
Head towards the burning wreckage in the forest straight ahead. There are two groups of KPA soldiers, one directly in front of you, and one to the left near the brook.
Kill them all and then walk towards the green beacon. Pick up the camera and also the shotgun and SMG ammo on the box to its left.
Continue running forward. Use your suit strength jump when you reach a cliff to rendezvous with O'Neill.
Follow O'Neill until you reach a cutscene.
When you have control again, you'll be driving an ASV. Its turret is very effective against both vehicles and soldiers alike.
Follow O'Neill up the road. Feel free to blow up KPA vehicles and soldiers if you want. Otherwise keep driving forward.
When you see a KPA rocket soldier on top of a small building, aim at the barrels next to it with your turret. You should be able to destroy everything quickly.
More KPA forces will attack you as you continue up the road.
Tip: If your vehicle accumulates too much damage, get out and find a replacement. Once your vehicle's damage meter gets to 100% you will die, so keep an eye on the bar. There are many unoccupied vehicles along the road.
Tip: Always aim for red explosive barrels if you can. The resulting conflagration will almost always instantly destroy whatever KPA forces are near by it.
There will be a gas station down the road. Some concentrated fire should bring the house down.
Eventually you'll reach the bottom of a hill with KPA forces firing at you from the right. Follow O'Neill up the hill to a landing zone with friendly forces. Your next task is to secure the area.
Quickly swap out your assault rifle for the precision sniper rifle. KPA soldiers will attack you from all ends. Fend them off with your arsenal of weapons.
Tip: Don't be shy about throwing lots of grenades. There are plenty of grenade boxes around to restock.
When the initial area is clear, look over the ridge for pink smoke. More KPA forces will storm that region. Use your rifle to snipe at them.
Tip: Activating strength mode will also allow you to throw grenades further. Do this to throw grenades over the ridge while under cover. This should soften up the enemy a bit.
When the objective is complete, get back in a vehicle and continue driving down the road.
The KPA will set a roadblock directly ahead. If you're feeling especially adventurous you can attempt to take it out. Or you can be more prudent and take a detour to your right. There will still be enemies, but they will be less concentrated. Watch out for the KPA helicopter as well. Keep driving and eventually you'll be at the harbor.
O'Neill will provide air support for you as you storm the facilities.
Make your way to the weapons cache marked by the yellow marker on your radar. Next to the trailers on the right side are some anti-vehicle mines and a rocket launcher.
Watch out for the enemies inside the building. There will be a nice FGL40 Auto Grenade Launcher and some ammo on the second floor.
Note: The FGL40 has two modes of fire: EMP and Frag. You'll probably want to use Frag for now, but the EMP mode will come in handy later.
After picking up the FGL, make your way to the trailer marked on your radar by the green dot. Go inside and use the laptop to access the KPA network.
The submarine doors are now open. Unfortunately, the harbor will be overrun by KPA soldiers as well.
Quickly run towards the submarine at the end of the harbor. There will be a parked APC at the start of the pier. Pull out your missile launcher and take it out.
Tip: If you are out of missiles, throw a bunch of frag grenades and use your grenade launcher to blow it up.
Make your way down the pier, taking cover while firing.. Use your frag grenades and your grenade launcher to thin out the KPA soldier's ranks. You'll want to move quickly because a mass of KPA soldiers will be on your tail.
When the coast is clear, get on the submarine and drop down to end the level.

Adapt or Perish

After the cutscene, you'll awaken in a winter wonderland. Your weapons are all gone, so you'll have to build up your arsenal again.
Walk forward and pick up the pistols on the ground. Break the frozen soldiers if you wish.
Turn around and strength jump on the crates to exit the submarine.
Quickly pick up the submachine guns on the box next to the sub. KPA soldiers in nanosuits will attack you.
Tip: Throwing a nano-disruptor grenade will temporarily stun the KPA nanosuits.
After you've cleared all three soldiers, get on the hovercraft.
Drive as fast as you can up the path without stopping. Aliens will attack you, but you have no recourse for them as the hovercraft has no weaponry.
Follow the path around the village and continue up the hill. You will see the general's hovercraft. Keep following it without stopping. Emerson will act as your GPS.
You will see the cargo container and some wrecked ships. Drive forward until you see the KPA fighting a giant alien. Ignore it and drive around back. Watch out for the spiked mines on the ice.
Get off the hovercraft and strength jump back up to the road. You'll hit a checkpoint.
Continue on foot up the path. At the broken bridge, drop down and head up the path on the left. You will encounter flying Alien Scouts along the way. It will be fruitless to fight them now, though. Make sure your suit is set to speed and rush towards the green marker.
Eventually you will meet up with Eagle Squad after strength jumping over some rocks. Pick up the Gauss Rifle and ammo next to the soldiers. Now you will be able to fight the aliens fairly.
Continue forward and take out the aliens with the help of your squadmates.
Follow the path until you reach a couple of KPA jeeps firing on a large alien. This isn't your battle, so feel free to ignore it. Get off the path to the left and continue forward. Make sure your speed mode is activated and make a beeline for the tunnel entrance. Feel free to kill only the aliens blocking your direct path.
As you close in on the tunnel entrance, you'll see a jeep fall from the sky like a piece of paper. Uh-oh you're actually going to have to fight that thing.

Boss Fight: Alien Exosuit

This isn't as tough as you might think it will be. The Exosuit's main attack is a heavy laser beam that it shoots from its jaw. When you see it preparing to fire, switch to speed mode and take cover behind a trailer.
Scour the trailers on each side of the area for an FGL40 and a missile launcher.
Use your missile launcher and FGL40 to aim at the Exosuit's jaw. If you run out of ammo for your launcher, there's another one nearby the trailers on the left.
Lesser aliens will join in on the fight, but feel free to ignore them to concentrate on the Exosuit.
Once the Exosuit is destroyed, pick up any ammo that you may want and run to meet your squadmates in the tunnel. You don't have to kill the remaining aliens.

Frozen Paradise

As you walk forward, sniper fire will hit you.
Switch on your cloak mode and take cover next to the downed car. Take the precision rifle and snipe the RPG-toting soldier on the ship in the distance. Your teammates should have taken out the snipers for you by this point.
Tip: There is more ammo to the left of where you start off.
Continue forward down the road. a little bit. When you see a ramp to the bottom floor, jump down.
Kill the KPA nanosuit soldier that emerges from the opening near the ship.
Switch to strength mode and strength jump up the platforms next to the ship. If you keep jumping forward like this, you'll eventually find an entrance to the ship.
Pick up the gauss rifle and the shotgun in front of you.
Several nano soldiers will attack you here.
Tip: Use your nanodisruptor grenades and the emp grenades from your FGL40 to disrupt the enemy suits. While they are stunned, quickly pump them full of shotgun lead.
After the area is clear, head towards the brightly lit corner and go through the door.
Make your way through these hallways. Pay no mind to the creepy objects moving here.
Drop down in the hole when you get to it.
Be careful, the enemy soldier in front of you is not a frozen human. It's a KPA nano soldier. Equip your shotgun and pump a couple of rounds in his back.
Several more KPA nano soldiers will attack you at this point. Take cover and throw out nano disruptor grenades. Quickly close the gap with speed, and shotgun them. You should prevail in the end.
Look for an area on the left side with a vending machine and a hole in the ceiling. Strength jump up to the next floor.
Pickup all of the goodies here and then jump off the ship.
You will see General Lee's convoy moving along the cliff. Move forward to intercept them.
Switch to speed mode and quickly dash across the ice to the path.
Run up the path, killing the two nano soldiers on the way.
Run through the caves until you emerge from the other end. You will see a jeep firing at an Exosuit. Ignore them and follow the frozen river to your left. There will be three nano soldiers to kill on the way here.
As you round the bend, equip your Gauss Rifle. A sizable number of Alien Scouts will attack you here. There are too many of them to simply run by them, so get their attention and then run back for cover. Kill them one by one.
Continue running until you get to the edge of a cliff. Stand by and watch the giant Aliens push around some wreckage. When they disappear, drop down and walk up the path on the right.
Strength jump over the gate and be prepared for battle.
Make sure your Gauss Rifle is still equipped. You will be fighting a lot of Alien Troopers and a Scout here.
Tip: Activate strength mode to make your Gauss shots a one hit kill versus the Troopers. You may also want to put on a combat scope to aid you in aiming.
When they are all dead, run up to the mine entrance to meet up with Eagle Squad.
The next sequence will be fairly challenging. You have to defend Cupcake for 4-5 minutes while he blows open the mine entrance. A lot of Alien Scouts and Troopers will attack you here. Your first priority is to take out any Troopers that have managed to break your first line of defense. Secondly, you need to destroy the Scouts ASAP, as they spawn more Troopers for you to deal with.
Ignore the order of one of the soldiers to pick up C4. It will be fairly useless since all of the aliens fly anyway. You will be using your Gauss Rifle almost exclusively during this battle.
Pick up a Missile Launcher from the weapons cache. Use it to fire at one of the three large aliens as they fly towards you. Make every shot count as you only have three missile launchers and there are several Scouts. Use your Gauss when you run out of missiles.
If you keep your cool and have a steady hand, you'll win the battle of attrition here.
Tip: Avoid manning the turret, as it will make you a stationary target.
An Exosuit will show up near the end of the battle, but don't worry. You won't have to fight it. The mine entrance will be open by this time. Go through it to end the level.

Below The Thunder

Pick up any ammo on the ground and continue forward through the dark cave.
If you get lost, head towards the green flares on the ground. They will light your way.
Eventually, you'll see some KPA soldiers firing below you. Throw some grenades to flush them out. Shotgun any stragglers.
Emerson will contact you at this point to guide you out.
Continue walking forward the flooded mineshaft and up the first opening on the right. Normal KPA soldiers will attack you here. Deal your favorite method of death to them.
When you get to a turret, stop before moving forward. Switch to your cloak mode and walk up the hill towards the manned turret at the top of the path. You'll want to make sure you have full energy before doing this so you won't be spotted.
Take the KPA squad unawares, making sure to neutralize the gunner first.
Keep moving on, killing KPA troops until you reach a hole to drop down into.
Note: Watch out for KPA troops with Gauss rifles here. One hit can either severely damage or kill you if you don't pay attention to your health.
Tip: Frag grenades and the shotgun are very effective here.
Throw a few frag grenades down the hole first to flush out the enemies. Then drop down yourself to mop up.
If you get disoriented, check the walls for an arrow pointing in the direction you need to go.
As you round the bend, you'll find several KPA soldiers and a turret. Crouch behind cover and lob some frag grenades over. Switch to cloak and get behind the turret to disable it. Mop up any remaining enemies.
Hug the wall on the left and run forward down this long hallway towards the pile of debris on the left. (If you go right, you may get crushed by the falling ceiling.)
A KPA Jeep will be driving towards you. If you still have a land mine, place it in front of the pile of debris. With luck, it will be in the path of the jeep as it drives towards you. Failing that, toss a couple of grenades at it to blow it up.
Remain behind the cover of the debris. An entire squad of KPA soldiers will advance on you behind the jeep.
Switch to strength mode and lob grenades over your cover to thin their ranks. Use your Gauss Rifle to snipe at them while you can. If they get close, pull out your shotgun.
Continue down the long hallway, killing KPA soldiers.
When you see a green sign pointing right, turn down that hallway through a section marked "B".
Before you enter the next room, switch on your cloak.
Immediatey turn towards the right and go in the little security room. Grab the guard and knock him out. Wait for your energy to recharge and then activate your cloak again. Go around the room, disabling all of the soldiers.
Note: It's possible to complete this entire section without having to fire a single shot.
When you are finished, make your way to the right side of the second floor. Go through the door under the sign marked "C".
Get ready for a large skirmish with the KPA in the trainyard.
There are two turret gunners on the far side of the area on both sides. Other than that, there are no other special strategies here other than take cover.
Tip: There's a room you can duck into on the right side of the area. Use this area to create a choke point for enemy soldiers to run into. There are also ammo and grenades in here.
After the area is secure, make your way up the stairs on the opposite end of the room. Duck into a room on the right at the end of the walkway.
Keep proceeding through the hallways until you reach a cutscene.

From Hell's Heart

You start the level on a moving train.
Make your way to the cars in the front by jumping. When you can see three KPA soldiers, stop and snipe them with your Gauss Rifle.
Your goal is to stay on the train until it reaches its destination. This won't be a walk in the park, as the KPA will throw helicopters, soldiers, and vehicles at you.
Tip: Head for the car with the turrets on the north and south ends of the car. (Not the ones facing outwards) These turrets can swivel 360 degrees, which is a huge bonus. The other turrets will stop turning after a certain point. The turret on the north end fires anti-vehicle rounds, so you may want to get in that one.
Tip: As always, aim for red barrels if you see them. You can blow up almost anything that attacks you, including the helicopters. Try to take out what is immediately shooting at you. Make sure your suit is set to armor mode.
The train will eventually stop and Emerson will tell you to shut the train down permanently by infiltrating the tower.
Stay a couple of minutes and pick off any remaining enemy soldiers while you are still on a turret.
When you are done, get off and start walking up the hill towards the tower.
As you come up the ridge, switch to cloak mode. You will be able to take out the first few guards without them knowing.
Note: O'Neill will be providing you air support. However, this doesn't mean that you can't help him out too. Enemy soldiers will be so distracted by him, that they will stop paying attention to you. Take this opportunity to snipe them from far away. Make sure to take out the KPA soldier manning the turret.
With the area secure, head to the control tower. Climb up and activate the... oops, looks like someone beat you to the lever.
Note: If you need ammo, go into the building opposite of the tower and pick some up. There's a missile launcher in here too if you need it.
Grab the ammo in the tower before making your way back to the train.
The train will start moving so you may have to activate speed mode and then switch over to strength to jump back on it.
Go ahead and make your way back to your favorite train car turret.
Be prepared up ahead, as an enemy train will approach from the left. Spot their gunner and kill him before he kills you. There are two gunners on the train.
Note: O'Neill has run out of ammo, but he will spot targets for you. Listen to him and he will make your job easier.
Ignore O'Neill when he tells you to throw grenades. Your turret is more than adequate in taking out the enemy gunners.
When you reach the swamp area, O'Neill says he will meet you up later, as he cannot see anything. Fortunately for you, the upcoming ride is fairly uneventful.
Eventually, the train will slow and stop as the aliens have come for the container. Get ready for a massive battle.
The first wave will be a bunch of Alien Troopers. Shoot them down with your turret. Aim for the Trooper that shields the other ones first. He may be hard to spot, but look for where the green lines are emanating from.
This time, three Alien Scouts will join the fray in addition to more Troopers. Fortunately, the heavy turret does good damage to them. Focus on the Scouts first, as they do the most damage. When they are all killed, mop up the remaining Troopers. If you do this right, you should be able to fend off the attack without having to leave the turret.
When the train stops at the bridge, get off the turret. Make your way to the front of the train for a cutscene.

All the Fury

After the lengthy cutscene, you'll find yourself in the jungle. Your objective is to reach the airport and retreive the container.
Activate your cloak as soon as you spot enemy movement. Sneak up to the rock where the KPA soldiers are and take them out quickly. A jeep will drive towards you on the right. Throw a couple of frag grenades at it to dispatch it.
The coast should be clear until you get closer to the airfield. Bear to the left side of the airfield.
You should see two soldiers patrolling the path. Activate your cloak and neutralize them quickly. Three more soliders will attack you, kill them too.
A sniper will be perched in the watchtower on the left corner of the airfield. Cloak, line up your shot with your Gauss Rifle, then switch to strength mode on your suit and fire. He should die in one shot.
Continue walking along the left fence of the airfield until you spot a hole. Use it to get inside.
Emerson will mark the location of the container on your radar now. Start walking towards the green marker.
At this point Emerson will put three secondary objectives on your radar. These are munitions trailers, in case you need to restock.
There will be large amounts of KPA soldiers here. Use your discretion in removing them.
When you have cleared the area in front of the first large building, walk around to the right side of it. You will see a ladder here. Climb up and you will have a great view of the area where the container is.
A tank will be firing at you near the container. Switch to your missile launcher and take it out from afar. Remember to stay zoomed in and keep your reticle on the tank until the shot hits. Pick up another missile launcher here on the roof.
A helicopter will fly in from the left eventually. Shoot two missiles at it to bring it down too.
Tip: If you have enough sniper rounds left, use this opportunity to pick off the enemy soldiers you see on the ground.
When you are done, get back to the ground and continue making your way towards the container.
Once the container is secure, Emerson will order you to get to the comm tower to guide in a VTOL.
The next part may get a little dicey. Run forward through the small gate next to the last munitions trailer. Walk forward until you see a tank. Empty your missile launcher on it, blowing it up. Run back to the munitions trailer to pick up another missile launcher. Return out to the airstrip and look straight down the long end. You should see another tank here. Destroy the tank and then get into the APC next do the gateway.
Drive south along the runway, killing soldiers.
You will see an unoccupied tank on the left hand side. Quickly drive to it, get out of the APC and get into the tank.
Use the tank's missiles to destroy the two enemy tanks that will attack you here.
Tip: Pressing Mouse 1 will fire the cannon. Pressing Mouse 2 will fire a missile. Beware, you have a limited supply of missiles.
Drive along the runway until you are close to the comm tower. Another tank will be here. Hopefully you have enough missiles left in your tank to destroy it. Otherwise you will have to get out on foot and use your own missile launcher.
Get out and make your way towards the tower. There will be large numbers of soldiers here. An APC will be patrolling the east end of the area as well. Utilize every weapon in your arsenal to fight your way to the tower.
Note: Watch out for the soldier with the Gauss Rifle perched on a landing of the tower. You may want to snipe him out of there ASAP, to ensure you don't die randomly from being sniped.
Tip: If you need more missile launchers in this area, there is a soldier on the north end of the tower area that carries one. There is also another missile launcher next to the comm tower itself on a crate.
Be sure to clear out the area before climbing the very tall ladder into the comm tower. If you fail to do so, you will most likely be shot down by an enemy as you are a sitting duck while climbing up.
Use the radio in the comm tower.
The sky will darken, and a large contingent of aliens will descend upon you. Quickly run down the stairs using speed mode.
Your goal is to reach the downed airplane in the center of the runway to obtain the experimental PAX weapon.
Keep speed mode activate and run back towards the airstrip. Find an unoccupied vehicle and get in. Drive towards the downed airplane and find a place with good cover to get out.
You will be fighting a TON of alien Troopers and Scouts here, including an Orange Scout. Hopefully you still have your Gauss Rifle. Take cover in the plane wreckage and have your strength mode activated.
After you clear the area around the plane, then go in and grab the PAX.
Head down the runway towards the giant Exosuit.

Final Boss Fight: Orange Exosuit

Be sure to clear the area of any lesser aliens before attacking the Exosuit, otherwise you will be very annoyed.
The Orange Exosuit has three main attacks.
If you are far away from it, it will launch four blue homing missiles at you. These missiles will track you very far and very accurately. Your best bet is to shoot them out of the sky before they get to you. As a last resort, you can switch to speed mode and run out of the way right as they are about to hit you.
If you are closer to it, the Orange Exosuit also has a twin blue laser attack and a powerful missile attack it will shoot from its jaw.
This fight is actually pretty simple. You want to close the distance between you and the Exosuit so you can use the PAX on it.
Shoot down the blue missiles as you make your way closer. If you know you are about to get hit by the missiles, switch to armor mode to absorb some damage.
Tip: You know you have damaged the Exosuit when you see it glow white.
When you are close enough to the Exosuit, switch to your PAX and let loose on it. Make sure you are in armor mode, and strafe around to avoid its attacks.
It will only take around 6-7 shots to down the Exosuit. When it falls, get out of the way of the explosion.
O'Neill will tell you to meet him back at the container. Switch to speed mode and run over to the container.
Congratulations, you have finished Crysis Warhead!