Two persons. Two lonely souls. They are looking for someone to be in their lives. They look pretty hard. Each constructed a lighthouse to signal other where to find them( the vertical black-and-white line at the edge). The soul-mate searching experience is mostly a negative one for them. That's why the lighthouse became more black than white over time. Or maybe the search criteria they use is too stringent, too black-and-white, so the others keep away from them. There is another possibility that they are too tender, too gentle, too subtle and the lighthouse is their defending mechanism. Anyway, somehow they found each other. Finally they align one to the other. And now the game can be started! (black and white squares in the center).