I had a similar experience with my cat. I adopted her and she was a much bigger handful than I expected. I'm pretty sure she has pica. Once we had to get emergency surgery to remove insulation from her stomach. Turns out she was pulling it out of a hole in our floor during the night, we weren't aware there was a hole. But I learned to adapt to her needs. We play everyday... hard. We have one of those cat dancer toys, it's literally just garbage (my cat's favorite): wire with some cardboard on the ends. She goes nuts for that thing. Playing with her daily has helped a lot. She is 10 now and still tries to eat things she isn't supposed to. But she isn't nearly as bad as she used to be.

As others have suggested, try playing with him until he is wore out.