3. The use of X and O in tic-tac-toe could be connected with a world-view which saw the cycles of time as a great hour-glass form:

The picture is from Hamlet's Mill and shows how the precession of the equinoxes slowly moves the frame of time in a cycle. Although the ancients did not have the hour-glass they certainly had its form.

The two cycles, one in the north and one in the south, are interconnected as if they were the bottom cicles of two cones, one standing upright and one upside down. The picture is in Hamlet's Mill associated with the peculiar form of Mount Meru (the world mountain):