Complete solution with answer and video walkthrough
The Slime King told them to go through 2 doors towards the East
Drag the red slime on the torch to get light. The shape on the wall lacks a green colored piece. Merge the blue and yellow slimes to make a green one. Put the green slime on the shape.


They must save Mary from the red slimes

They must find a way to get across

The Slime King confronts them

End the war between the red and blue slimes

They reached to the 2nd gate. They must solve its puzzle

Alyx must fill the bottle with the Fountain of Life's water

The cave is collapsing upon them! Find an exit

They are close to the surface, but they must find a way to dig out