I suggest District 21 in a shopping mall in KL. Super Fun there. My 9 year old daughter loves there a lot and can play all day there. I don't think you can find that kinds of indoor playroom in HK with only about RM58. For parents if not playing, pay RM10 for watching. Strongly recommended.
Regarding District 21, District 21 is located in a big shopping centre. For me, my relatives in KL drive me there. I think it is better to take taxi there, as I can't see a lot of public transport there. You can spend a day there. Hope it helps.