Not every dog thinks that a round of #fetch is doggie nirvana. Some would rather track interesting smells, or learn new tricks. Some would rather dig a hole to China. And some, of course, just want to see what’s next on Animal Planet. Dogs like to play differently, depending on their breed and their individual personality. But once you figure out which games wag your dog’s tail, you can use them to give him exercise, mental stimulation, and a sense of purpose. (Yes, even dogs