Fill multiple cleaned plastic jars with different scents and let your dog identify them by sniffing one particular scent you hold in your hand, and matching it.

Braid and tie multiple old t-shirts or jeans together into sturdy chew toys where you can hide pieces of your dog's treats or kibble.

Use a clean muffin tin and place in it multiple tennis balls or plastic cups on top of your dog's kibble to create a puzzle/slow feeder.

Cut multiple small holes in a tennis ball and place treats inside. You can also place inside it a squeaker for extra engagement.

Fill a shoe box or any cardboard box you have available in your home with shredded paper or shredded fabric and hide your dog's favourite treats inside.

Get a 2 x 1-foot long cardboard piece (the sturdier the better) and cut thin holes, big enough to squeeze through a few of your dog's tug-and-pull rope toys, for your dog to have to pull out of while you hold the cardboard up.

If you have a backyard, fill a big enough plastic container (depending on your dog's size) with sand for your dog to dig their toys out of. An indoor version would involve shredded paper or cloth.

Get a long enough PVC pipe and drill a few holes into it for your dog to have to move around as each piece falls out.

Fold a few towels on the floor, and hide treats inside one of them. Guide your dog with a leash towards them and once he realizes which one has the treats, ask for a sit and reward with an even better treat from your hand.

Mash up multiple paper bags (on their own or together into a big blob) and place treats inside of them for your dog to snuffle through.

Patience/impulse control-like training game: Purposely toss treats or your dog's favourite toy underneath furniture, where your dog won't be able to reach, and wait for them to learn (without any verbal cues from you) that the way to get to what they want is to wait quietly, longer and longer each time.

Use a 2-step ladder or any type of raise platforms (suitable for your dog's size and age) for your dog to have to get to step on and off of before you toss a treat for them to go find.