play·ground 
(plāground′)
(plāground′)n.
1.
a. An outdoor area featuring equipment designed for recreation and play, such as seesaws and swings.
b. An indoor area, such as a room at a community center, that is set up with similar equipment.
2. A field or sphere of unrestricted pleasurable activity: "Foreign affairs had been T.R.'s personal playground during his Presidency" (John Dos Passos).