how Singaporeans aren't very outdoorsy. But don't worry, the government is on it!
The cultural expectations here about the role of the government are very different. In the US, any sort of governmental steering (even something apparently non-controversial like labeling food with its actual ingredients) will be met by shrieks of outrage and accusations of a "nanny state". In Singapore, the government is constantly in your business, telling you what to eat, how to clean your house, how to speak (they have a whole campaign "Speak Good English" to discourage the local accent), and how to spend your leisure time.
Singapore has maybe the highest rate of myopia among children in the world, which is why the above sign was recently installed in our local park. But to me as an American the sign comes across as so bossy. The government isn't just warning you about the possible dangers of eye strain: they have decided exactly what you and your children ought to be doing.
I also find it amusing that playing outdoors is seen as strictly medicinal: it's assumed that no one would be outside just for fun!