How to give "falling" effect to this level, better?

I am working on stories first part in my game. It is a mini-game that you see after running away from computer.
You fall down in a computer inspired environment, and there is enemies & platforms for you to keep away.
I was looking at moving backgrounds. I'm moving them on z-axis (from +z to -z), like they are coming towards screen. They have a constant speed. There is a black main background with white highlights that look like you enter a dark room and someone opens lights. And then backgrounds start spawning and moving towards screen. Character will move left-right via accelerometer, and if a platform hits you (they have different features, breakable, non-breakable), you are pushed back. If you are in dead zone for a few seconds, you restart. That is how this level works.
(I recorded a little video of moving backgrounds, sorry for low quality.)

At the actual game, I'm thinking about putting a prompt to say user, "Hold your device parallel to ground, so experience gets better.", at the start of this level. But I'm unsure, is it a good way to tell user to get a specific position for each level? (I am going to use this for one level for now, but what if I make more levels like this?)

Maybe there is a way to give this falling effect to the user, more effectively. Do you have an idea?

PS. There is gold-ish colored lights on 4 directions. I make them to look like lights that is hitting on walls, but it looks like Camera is dirty... Do you think that needs improvements too, or is it good this way?

 

There are a few things that could make it feel more like you're falling:

• motion blur
• particles that fly toward the camera
• increase the speed over time
• have other objecs falling next to you at varying rates like debris from the floor that broke

You could also do something like stand the player on a platform before falling into the hole, then have the camera rotate forward 90 degrees at the start - this will tell the player that they're now looking down.

I think because it's so steady it's just like you're robotically moving through a tunnel like you're on a train or something.

 

Right now, I'm working on this. I will update video when I complete my current scene design idea.

My game is 2D. I don't know how to implement this in right way. Let me think about it a bit...

I don't know how to do this using Unity. I can draw some transparent sprites to give this effect, but I'm afraid it will be boring after a while; because I want this level to take around 5 minutes, Player will see same sprite animation again and again. If there is someway to implement this using Unity Camera and/or Cinemachine please point me in right direction.

Also @Serinx, thank you for your answer!

 

You could try using the post processing stack for motion blur but I've never tried it in 2d.

https://docs.unity3d.com/2017.4/Documentation/Manual/PostProcessing-Stack.html

You could make the debris move with the tunnel at different speeds, it'll just take some playing around to get the speed looking right.