40% of Hong Kong is country park so it is quite surprising that you didn't find any of it, particularly if you lived in DB where all you have to do is walk out of your door and onto some beautiful hills. And for things like kids' playgrounds (swings, slides, climbing frames etc.) HK has a far, far higher density than any other city I have lived in.
More details on the Country Parks here:
http://www.afcd.gov.hk/parks/parks_e.htm
and on some of the other leisure facilities here:
http://www.lcsd.gov.hk/en/ls_fac.php