A dining table, a cotton sheet, and a warm lamp become a city. Give the kids a job: “You are in charge of the door.” Responsibility is a kind of play.
Rotate three toys onto the living-room rug and put the rest away. Scarcity, oddly, increases invention.
Tape a paper road on the floor. Suddenly every block and figure has somewhere to go.
None of this replaces a well-chosen toy. It just reminds us that play is a practice, not a purchase.