Games and exercises for dobermans?

Any kind of trick that keeps a dog's mind occupied is the same as physical stimulation. For instance, you could teach him the name of a toy, hide it in the garden, and get the dog to track it down. Any kind of obedience issue you may have, you can improve on with training in the winter, rather than being out and about. Tug games are good, PROVIDED you have a good 'release' command, otherwise it becomes a dominance game. Playing with dog friends is another good way to burn off energy - our Dobie gets the chance to play with others down the park every day - even if it is only a short play, it breaks the day up and releases energy. One thing we did try with some success when it was too cold to go out was to create jobs for her in the house - like closing doors, putting toys away, etc. As you have a member of the most intelligent breed of dog in the world :), he will lap this up! Good luck!