Boundary games are all about teaching our dogs the vital job of staying on a boundary until released. Once your dog has the basic concept you can add in mouse and airplane games.
By adding in the mouse and airplane games, we can duration, build stillness, focus, self-control, tolerance of frustration and more in dogs that have difficulty calming down! Mouse game can be played on the boundary, or if your dog is experienced on staying on the boundary you can up the ante and play mouse on the floor. Note that if you have a very calm dog already who settles well on the boundary, then these games may not be needed.
For dog-dog reactivity, boundaries are a key component of teaching transitions between environments which can help maintain calmness instead of arousal.