In the park near my apartment is a Kinderspielplatz (der). While this translates quite neatly to “children’s playground,” it seems a bit stilted to add the word “children’s” at the beginning. Yes, Atlantic City calls itself “America’s Playground” without intending to suggest it is a place only for children, however the typical image that comes to mind when someone says “playground” is of swings and slides and teeter-totters. Dict.cc has an entry for der Spielplatz – simply “playground” and also offers die Spielwiese – literally “play meadow or play grass” – and the lovely der Tummelplatz – “the romping [tummeln] place.”
The same dict.cc entry offers words for an indoor and an outdoor [play]ground, der Hallenplatz and der Freiplatz. Der Hallenplatz is a bit strange – “a hall place” – although in British English we do have the collocation “sports hall.” But der Freiplatz feels awkward unless one already knows the word das Freibad – “outdoor swimming pool.” The “outdoor” or “open air” meaning of frei is quite a bit less common than the “free” or “available” meanings. For instance, one thing you learn pretty early on is to say »Ist dieser Platz frei?« when you mean “Is anyone sitting here?” and everyone is always on the lookout for events or objects that are frei in the sense of not costing anything (kostenlos). Using cannoo.net it became clear however that frei is a pretty productive adjective. I’ll leave you with just one example, der Freigang, which when paired with bekommen means “to be let out on parole.” Having finished this post, I will let myself out to play!