SAN DIEGO — Domino toppling — it sounds like a kids’ game. To DeMond Nason, 42, and other adult aficionados, it is anything but that. All his life Nason, who was born in National City and graduated from the San Diego School of Creative and Performing Arts, had turned to art as his creative and therapeutic outlet — tole painting, ceramics, clay, watercolors, drawing, photography … Then he discovered dominoes. In 2017, he stumbled across YouTube clips of domino drops. He listened to the soft bump of the cascading domino bricks and found it peaceful and soothing: “It was just beautiful to me.” …