Snow can be the perfect opportunity to up your hide and seek game. If you have a mostly empty yard and couldn't play well there before, now's your chance! Shovel up some walls and hiding spots to provide your dog some additional challenge.
While a maze might be easy, an obstacle course is just as fun. Build ramps for them to walk up, down, and across, piles for them to jump over, and if they're small enough, tunnels for them to run through. There's no limit to your creativity as long as your design functions within the limits of physics!
If you end up with a fair amount of snow and have shorter dogs, making a snow maze or track is a great way for them to explore the outdoors without sinking into the snow. Grab a shovel and carve out a maze or a track for them to burn around.