Aw, I'm sure you are a good player! Maybe you can learn more about how to play from your dog.
I actually get down in front of Thor and return his play bows. I also play tug of war with him, during which I get in his face and play growl. I will put a sock on my hand and let him bite it.
I also chase Thor around my office (I know I sound completely crazy at this point, ha ha). I don't do this outside because I want him to RETURN to me outside, not run away. If I had a yard, I would chase him around there, though. He sort of knows the drill. If I kind of stomp my feet at him, he takes off running. Sometimes I throw a toy, which he attacks, and then we play "Keep Away". He loves hiding behind corners and peeking out to see if I'm coming after him. It's hilarious.
I honestly wish Thor liked other dogs more because I know I can't be the greatest play partner. I'm not nearly as nimble or quick as he is! I guess I'm all he's got though, and beggars can't be choosers.