How to reverse particles animation of tyflow?

[HuaLi]

Use the retimer settings.

I tried setting "retimer", but it has no animation:


  retimer_settings.mp4 (Size: 2.17 MB / Downloads: 337)

And, I am not sure wheather there are confusions between "reverse" and "play back".

so I make a definition: 

forward: the door begins opening, then the particles get out of the red box.

reverse:  the particles get back to the red box, then the door closes, all return to the original state.

play back: the animation is still forward, plays again.

I want to reverse the animation, not play back. sorry English is not my mother tongue.