Base “Leviathan Reef”
Follow the only path through the pipe and clear the room. At the bottom, activate the lever and you will see that a passage has opened just below. Return to him along the adjacent pipe and follow to the right. Climb a little up through the pipe and kill the enemies. First head left to the previous screen and pull the lever to open the door. Go through it, up, destroy the walls and drop the biomass into the red pool. Go back to the right and use the cobwebs to switch the lever. Kill enemies, go downstairs and go through the door.
Get to the reservoir and swim to the left. Activate the lever behind the pipe and go back downstairs. Swim through the opened opening. Activate the first savepoint on the left side.
Kill all enemies, swim to the right through a couple of pipes and find the second save point. Kill the robot from below to open the passage down. Kill enemies, swim left and hack the container to get the new ability “Hydrophilia”. With it, you can squeeze between small cubes. Previously, you could not do this and just used the web to activate the lever behind these cubes. There are such cubes at the top of this room.
You will immediately turn into worms. Swim up through several such passes until you find the third save point. Keep in mind that your character turns into worms only in water! This happens automatically. Walk left and kill the huge robot. You will need to attack him with RMB then retreat behind the obstacles so as not to fall under a machine gun burst. After winning, fly down through the water between the cubes and use your large open eye.
Frontier – Marsh
Activate the lever on the left. Follow the left, down into the pond and swim between the cubes on the left. This will lead you to the laboratory. Lower the lever and follow to the right. Go around the turret (you can’t knock it down) down and use the sewers to get to the next level.
Science Center
Swim down, with a large biomass, make your way between the cubes and break the wooden planks above the lever. Climb up and to the left to dump your biomass into the red pool. Return to the lever and activate it with the web. Water will appear at the top right. Take the biomass, follow there and make your way between the cubes.
Kill enemies in the large hall. The robots are still locked, so follow the right through the door. Climb down, to the right and kill the enemy in the back room. Activate the lever. Two passages above the robots will open. Return to that hall and follow through the upper right passage. Kill the enemy, follow through the toilet stalls to the right and activate the first save point.
Next, you will need to climb up through the offices, kill enemies. There will be a pipe at the very top behind a wooden barrier. Break it, fly up and activate the second save point.
Fly down and activate the laser. The door will close from below. There is a passage to the left above it. Follow there, go up and dump the biomass into the water. Return to the locked door and fly downward by removing the grates. Activate the lever with a web, fly up and fly past the laser using invisibility. First of all, kill the soldier in the room on the left, deal with the rest and activate the lever. He will turn off the lasers. Fly down and find yourself at the door on the left. Fly even lower and activate the third savepoint on the left.
Go downstairs and activate 2 levers. You will open one of the necessary doors, but also release the first robot. Kill him, head back to the third save point and fly through the door above it. Activate the lever and go back through the doors. Be sure to use the lever to the right of the pool where you left the biomass to use the spider webs. The right door will close, but the left one will open. It is important!
After that follow to the right of the door, which was surrounded by lasers. You will return to the offices you moved up. Fly down and to the left to return to the hall with robots (already one). This time fly into the passage above the left robot (to the left). Activate the fourth savepoint. Use the same technique again, leaving the biomass in the familiar pool and activating the webbing lever. Return biomass, fly down and activate two levers to release the second robot. You don’t need to kill him! You can immediately fly down. This will get you to the new lever. Having opened the way further, follow the right.
Open another door, break the flask and take the new ability “Parasite”. You can now control the minds of other enemies. Press TAB and take control over enemies. Activate one lever, follow left and activate the other. Press TAB again to stop mind control. Go up to the hall with robots and follow the exit signs to the right. Get to the room with enemies. Take control of one of them and kill the other two. It will be easier. Activate the lever, go downstairs and soon reach the eye.
Frontier – Marsh
Follow left, flip the lever to change the water level, and then go down the pipe. Move between the cubes in the upper right to move to a familiar location.
Base “Leviathan Reef”
Move right and up to the save point, under which there is a door and an enemy. Grab it with a parasite and press TAB. The monster will move to the position of any captured enemy that is not protected by the suit. So it is here. Using this mechanic, go through the door to a new level.