I don't see a need for a new key here.
The properties can be easily modelled with sub-tagging of playground:
leisure=playground
playground:supervised=yes/no
playground:outdoor=yes/no
playground:indoor=yes/no
I agree in general, but the main issue with tagging like this is that I
bet most data consumers will just look for leisure=playground and that's
it.
__________
openstreetmap.org/user/AndiG88
wiki.openstreetmap.org/wiki/User:AndiG88
_______________________________________________
Tagging mailing list
[email protected]
https://lists.openstreetmap.org/listinfo/tagging