You have just entered the underground portion of the Lost Valley, with a view of a small waterfall and clockwork machinery to the right.
As soon as you step forward, you hear nearby wolves. They are on the ground below, and will need to be evaded or killed. After dealing with them, head to the left of the water and collect the first cog.
When you have this cog piece, you may either head to the second cog, or use this cog to start the machinery in order to grab the farthest third cog. However, you won't be able to proceed through the waterfall until you have all three cogs.
Climb the pathway left of the waterfall. The first portion is a direct climb, turning slightly to the left, before jumping on the right-hand out-cropping. Reach the waterfall side of that outcropping, and jump to the top, and proceed to the area behind the waterfall.
Run down the path and jump across the flowing river. When you climb up, you should see a broken bridge. Shoot it and it should fall down, allowing you to use the rung attached to it as a swinging pole.
Next, use the grappling hook to get past the river again. After climbing, you should be able to use the bridge. Attack the two bats approaching from the side, and pick up the cog.
To head back, head to the spinning wheel on the left, and grab the pole. Use this to grab the visible ledge ahead of you, and climb to the top. Jump to the alcove in the corner, and you should be able to reach a switch that opens an underwater grate.
Note that there are three wolves that attack when you return to the starting area.
Climb the ladder to the right of the water, and insert the first cog. This starts the first gears. Jump on the first pole, and use it to reach one of the two poles on the larger gear. Then, jump onto the ladder. You may insert the second cog or wait until you return.
Grab the ledge on the right, jumping across the gap, and finally reaching the platform that was above you.
Turn towards the wall above the entrance to the cave, and jump to the ledge. Shimmy to the right, and jump up in order to reach the rope. Swing on the rope in order to catch the ledge on the left-hand of the cave. From here, move to the right, and drop down on the platform.
Climb into the side cave and proceed through the tunnel. After the second low gap, you will be attacked by a bear, which can be safely attacked by backing up through the low tunnel portion.
Continue climbing up the cave. When you reach the upper platform with the .50 caliber rounds, turn towards the poles, and jump towards the ledge on the left. Use the ledge to perform pole jumping, and into the cave at the back.
When you run up the steps, jump onto the ramp, and jump just before falling into the pit. Grab onto the ledge, and continue to the right. When you are approaching the surface with the large medikit, watch for bats coming to attack (identified by a red arrow pointing to the left or bottom). Reach the platform as quickly as possible, and destroy the bats.
When you head down the tunnel, you will see wooden planks on the ground. These will break when you try crossing them.
After the fall, you should enter a green valley. However, raptors will start attacking. In addition to their regular attacks, one may make a scream and attempt a charge attack If it does so, roll out of the way, and retaliate once the crosshair becomes red. There are a total of six attacking raptors in two waves.
After the initial attack, the T-Rex will attack. In the cutscene, press the arrows shown to avoid taking damage.
The T-Rex has two bars shown at the top-right. The upper is the health meter, and the lower is the rage meter that fills if it takes too much damage in a short period of time. It is possible to kite the T-Rex to finish it, but this will be a slow process. There are two method that speed up the process.
First, you need to attack the T-Rex until its rage meter fills. It will retaliate with a charge attack, dodged by a roll in any direction. During the roll, watch for the crosshairs to become red - attack at this point to inflict more daamge on the T-Rex.
In addition, you will notice three spiked bars throughout the boss arena. If you provoke the T-Rex into charging towards them, and land a successful attack, you will inflict significant damage against it.
When defeated, you will need to continue with two cutscene events.
Climb the temple smashed by the T-Rex. The third cog should be in immediate view, but you also need to escape.
Swim under water and through the passage. Climb up the large pole, and use the ledges to reach the window above. This allows you to run along the side of the arena, which can be used to reach the exit.
There is a checkpoint at the small medikit. There is also a large medikit past the broken bridge.
Return to the main area. Once you get back to the waterfall, make a jump into the water to avoid damage.
With other two cogs, head to the machine once again. Jump to the second platform, and insert the cog if it isn't ready already. Climb the ledges on the right to reach the third platform above. When the gear to the left turns its platform, you can jump and run across it when it is flat. Insert the third cog and pull the lever.
This activates the mechanism that stops the waterfall, providing access to the exit. Jump into the water to avoid death, and swim to the newly open door.
There are two artifacts on the level.
- This section is a stub. Help us , and you get a cookie.
There is one relic.
- This section is a stub. Help us , and you get a cookie.
- Enter the water at the starting area, and swim towards the entrance. This has a small health pack.
- In the area where you collect the second cog, shoot the support holding up the bridge. Use the grappling hook to swing to the other side, and grab onto the bridge as a ladder. Jump to the right onto the cave opening. You can collect the shotgun here.
- From the platform you use to reach the T-Rex, you may notice an alcove below the ledges you are using. Drop down and retrieve a large medikit.