The Paper Ball Game was originally invented for our hamsters, many many years before we ever thought of getting dogs. It was pretty simple in that incarnation: put Yogie in brown paper bag, crumple bag into a ball, drop bag in hamster cage.
The dog version is basically the same, except that there are a bunch of paper balls and they are piled up together in a container. This allows you to sneak in a little variation, if you're so inclined: put low-value treats in one kind of paper bag and high-value treats in another kind of paper bag, and watch how quickly your dog differentiates between the two when deciding which paper ball he's going to grab first.
Here, the white paper balls contain Wellness Pure Beef jerky treats (each one cut in half so there are actually two smaller treats inside each paper ball, which gives the dogs about 0.05 seconds more entertainment as they sniff out both halves), and the brown paper balls contain scraps of roast chicken from yesterday's dinner.
The dogs wait for the signal to start playing (they're not on a firm "Stay" here, they're just not allowed to take any balls until they get permission):
...and, once released to do so, both immediately go for the brown paper balls. (Then they scurry off with their treasures to opposite ends of the house, which is fine because it prevents them from squabbling.)
Pongu used to be terrified of even approaching the cardboard box, let alone touching a paper ball and risking its terrifying crinkle noise, but he got over that pretty quickly after watching the foster monsters take all his treats the first time. Jealousy's a powerful motivator. Now he loves the game.
Mostly the dogs are pretty polite about unwrapping their treats instead of ripping the bags to shreds, so often you can get multiple uses out of each wrapping. I also use packing paper if it's clean and not too flimsy.