Is there a way in blender cycles render engine to render a scene backwards instead of forward?
Once you've rendered the animation to an image sequence, import that into the VSE (in a separate .blend if you prefer). To add the image sequence, press ⇧ ShiftA> Image and select the images in the sequence.
Ensure the scene render dimensions, end frame, frame rate, etc. match your image sequence.
Set the output settings to render to the video format of your choice.
Enable Backwards if you want to render the frames in reverse order: