Level 6: Treehouse
Get to the Scientist to help find Val
The building in which you begin has no enemies - at least, no enemies that can actually hurt you. You should get your first good look at some of the Tridgens that you’ll be fighting later on, though.
When you reach the door leading to the outside, Doyle will radio in with your first objective. At the same time, you should hear a vehicle approaching from your left. The soldiers aboard will be scouting around for you, but if you stay out of sight, they should be distracted by a couple of incoming Tridgens. If the Tridgens don’t emerge from the forest, you’ll probably have to take out the mercs (who are a bit tougher than the previous versions, but drop bits of armor when they die) and then deal with the Tridgens as they come at you. These Tridgens are of the primate variety, meaning that they have no projectile weaponry, but will instead jump and slash at you when they get fairly close. They’re extremely powerful when they actually manage to hit you, and are fully capable of killing you in just a couple of hits, so engage them from a distance with your M4.
After the nearby threats are dead, you’ll have to continue on your way to the Supervision building. You have your choice of paths; you can either walk along the suspended platforms among the trees, or grab the 4WD and drive to the entrance. The latter path is a bit easier, and will probably let you arrive at the Supervision building without wasting any ammo, but the path is a bit circuitous. If you can turn the vehicle around and point it towards the jungle, taking every left turn along the path should let you reach the rear side of the Supervision building. You won’t be able to get it - all the doors are locked on the ground level - but you’ll be close to the broken walkway that leads to the building’s roof. You’ll probably have to blast a few Tridgens to clear the path, so switch your vehicle over to the rocket launcher and fire at anything that moves. If, on the other hand, you decide to proceed to this area along the walkways, let the mercenaries do the bulk of the shooting, but be sure to take down anyone directly in your path. By the time you get to the enclosed Tridgen zoo, you’ll probably have to start shooting at the Tridgens on the ground below you in order to clear the path to the Supervision building.
The first room of the Supervision building contains a couple of Tridgens; engaging these things in close quarters is decidedly unrecommended, so unload a clip from your M4 into one of them, chuck a grenade, then retreat to the exterior and reload. They’ll likely move to the doorway to follow you, so move around to the west side of the building to find another entrance to the same interior room and blast them from behind. After they’re dead, head through the red-light door to find the very dead scientist and his keycard. Use the keycard to open up the nearby room and flip the switch here; this will open up the path to the helipad at the rear of the building.
Enter the Bunker
As soon as you do this, though, a couple of soldiers will start making their way to your position along the previously-locked path at the rear of the building. You can feel free to stand and fight, if you wish; you’ll probably have to fight them eventually anyway. In any case, your next goal is to reach the garage of the Supervision building, which is down the nearby stairs inside the complex. A Tridgen and mercenary clutter up the hallway on the way down, and two more Tridgens await inside the garage itself, so stay on your toes. The garage also contains a few grenades and some more ammo, so load up before getting in the Big Truck.
After you’ve unlocked the door and driven outside, you might want to try reclaiming your 4WD if you left it nearby. If the area is clear of Tridgens, and you think you’ll have a relatively safe walk, then ditch the truck and get your...other truck. Switch over to rocket launchers, if you wish, and drive up to the helipad, dispatching all of the mercs who’re waiting for you there. When they’re disposed of, grab the other 4WD (which will probably be less damaged than the one you’re driving now, if indeed you’re driving one at all) and head down the little dirt path.
As a note, the next section can get a little hairy. If you’re not looking for a huge firefight, there’s a walking path to the northeast of this helipad that will bypass some of the defenders ahead. You’ll wind up at the same tower either way.
Get explosives from the tower.
Plant explosives at the rear wall of the bunker
As soon as you spot the bunker in the distance, hop out of your vehicle and use your binoculars to scout around. When you have a good idea of what you’re up against, get back in and use your rocket launcher to clear out the road block ahead and a couple of the soldiers up in the bunker itself. You can’t access the bunker just yet; you’ll have to travel for a bit to reach its rear side.
When you’ve destroyed the road block, hop into the mounted minigun nearby and use it to clear out the rest of the assorted mercs in the area. Don’t proceed on foot just yet, though; there’s a sniper in the bombed-out building across the bridge from you, who you’ll want to destroy before moving on. If you can jump the roadblock with your 4WD, a rocket or two should take care of the problem; alternatively, you can lie prone next to the minigun and strafe left and right until you get a shot at the sniper with your own sniper rifle or the M4.
You’re actually able to take the 4WD across the stone bridge here, although it’ll take some creative driving to get past the broken concrete along the way. If you wish, you can even drive it all the way up to the tower, but be careful for more mercenaries along the road. When you reach the tower, scope out the roost at its top; there may be another rocket-wielding merc up there, so step lively when walking around. The explosives are near the base of the tower, but you may want to walk up to the top and grab more rocket ammo from the hopefully-dead merc before proceeding onwards. If he’s not dead when you climb the ladder, however, you can expect a rude welcome.
When you finally reach the footbridge leading to the rear of the bunker, take one last opportunity to use your binoculars from a distance. If you still have your 4WD, feel free to blast off a few rockets towards any enemies you see. After you’ve weakened up your foes a bit, cross the bridge and place your explosives on the cracked section of the bunker’s wall.
After you breach the walls, a helicopter gunship will fly in and start pounding away at you. Dispatch its gunner, and any soldiers inside the bunker itself, before moving on to end the level. Don’t miss the suit of armor on the shelves near the doors leading to the underground portion of the bunker.