I always play the game where you put a treat under 3 cups on tile and they have to knock over the cup to get the treat. What are some other games that make them think?
If you have a muffin tin, then put a treat in each little slot thingy. Then put something round over top of it. Like a tennis ball in one, or a crumpled of paperball in the next. Be creative. Your dog will eventually get them all. It makes them think how they can get their treat so they will either have to lift it, or knock it over.