accordingly the advertisement, it's a clever trick but no rocket science: 2 bit binary counter

something like 00= stop, 01= right, 10=left, 11=forward

look at the photograph, you can see that the disk has two layers of squares

of course, I'm just guessing and it may be rocket science :-) but to be sure I would have to buy the toy and usually I become more interested in doing something like this myself than buying a ready made.