Overseer

Overseers are thin, plantlike creatures which pop out of the ground rapidly and appear to be watching slugcat. One in particular has taken an interest in guiding slugcat to serve some goal...

Yellow Overseer
The yellow Overseer you meet at the beginning of the game (known by some as "Iggy") acts as a basic tutorial and as a guide.

Signs
As well as teaching the player the controls, the yellow guide will point to things and put a symbol next to the arrow. The symbols are (based on videos of people playing this game):

An upside-down 2 with 2 lines above it: This symbol seems to mean "there is a predator that way" when the yellow guide points to an edge of the screen or to a tunnel, and "this wants to eat you" when the yellow guide points to something. This symbol will change between yellow (the color that the symbols are normally) and red (probably to make it clear that it's dangerous).

A bat outline: "There is food that way".

Occasionally you will be shown images inside yellow octagons, clumsy attempts to communicate important messages about what you are expected to do.

Blue Overseers
Blue Overseers appear after a while, like the yellow one. Blue Overseers can be seen interacting with each other by connecting their arms/tendrils with each other which will cause little sparks. Occasionally, a careless blue Overseer (besides the guide) can be killed by a curious scavenger that throws spears or Rubbish at it.