How do I - Make EVERYTHING slow motion

The title may be enough, but...

I am making a game, and I want a "slow motion" feature like GTA-V's for example.

However, I cannot find an easy way to do this without adding LOTS of events.

Has anyone done this or can it be done?

Thanks in advance,

EFF

would "system set timescale to 0.5" do the trick?

Thanks for the reply! I will try that later!