how to make a plataforme game with 3d depth

I want to make a plataform game like this video

How can i make that 3d background with the side walking game?


Well just like you would make a 2D platformer.
But with a few slight changes:

1.) Use 3D models
2.) Whenever using Rigidbody fix them on the Z -plane so your characters dont somehow fly off into the distance.
3.) Set the camera to perspective and mabye tilt it a little bit.

That should be all.
Since the camera is in perspective-mode you can change the depth of things by simply moving them towards or away from the camera.

Good Luck