playing who? I mean, I'm going to guess that he had a hand in the journals, but are you saying that the reason he even allowed Dipper and Mabel to hang out at the shack was to get them to do all the legwork for him despite not having a single clue about anything?
I was meaning the Journals, but you might be on to something. What if you need to be a kid to do curtain tasks to use the journals.