When you start to design your app, decide the size of the playspace. Is it the size of a tabletop, a bedroom, or as big as the world?
The experience should fit the environment. For example, a board game might work best at table scale. On the other hand, a scavenger hunt will need a much bigger area.
Show users the ideal size and the perfect conditions for your experience. Set their expectations right away. You can still surprise them, but let them know where those surprises might happen.