Yep, I'm only missing the green area. Which is on the left of the sewer. It keeps telling me I need a gas mask. However the right side I have it all done just can't go further I think cause the gate needs a card and I don't have that. I have slime as an ally, he helps me with the right area. So, yeah the left area that gives off a green glow, is the area in the sewer that's talking about the GasMask.