This one is called Light-N-Logo Tracking (though it is really just light tracking!) It also features simple GUI Program Maker programming with the S2.
The Target Bot S2 is equipped with an LED flashlight in a container (two bowls stuck together sticky tack) complete with the Parallax Logo - it rotates clockwise and counter-clockwise (randomized by a coin toss) around the second S2 Tracking Bot. Can the tracker follow? See photos and video.
This is similar to Light following but a bit easier since the Tracking Bot rotates in place. The Target Bot just runs a circle with changes of direction.