Hi Chris- I used to be a vet technician, so I know a little bit about this. When a puppy is first born, they will bite their own brothers and sisters of the litter for play. When the play gets too rough, the other puppy yelps to let them know that it hurt and next time to be more gentle when they want to play. Your puppy now considers you to be a part of his "pack" and he is playing with you the same as he would with his kind. I know it sounds crazy, but this technique has really worked! Next time you are playing and he gets too rough, make a yelping sound. You will notice your puppy stop and look up at you because you are now communicating something that he understands- Oh, I was too rough! He will keep trying to bite, but each time you will notice less and less pressure on your skin till eventually it's a soft grazing of his teeth, then eventually nothing at all. But remember to yelp every time he bites too hard, you are letting him know what pressure is tolerable. Also, your puppy is teething so get lots of chew toys. Throwing a ball or toy is a better way to play then tug of war. Tug of war teaches puppies how to fight, like when human boys practice fighting with each other. Once you understand how your puppy is communicating to you, it's alot easier to raise them. Some people smack their dog for doing wrong, but that only confuses the dog and he wonders why his family member hurt him.
Oh, I almost forgot- after you yelp (his language) say NO ( teach him your language ).