So this idea of creating “3D” illusion art, while still being in 2D, originally came to me after working a while ago on a small 3 person team project, and seeing the challenges that came with a team of that size.
I’d been wanting to experiment with creating a mostly 2D environment in the style of games like Bastion and Bravely Default for a while now - the visual style of each one struck me as being both beautiful and yet deceptively simple in their construction, and I took much of my visual inspiration for this project from them.
So that I didn't have to draw everything in a distorted way, I set the camera in Unity at a slight angle so the player can see the horizontal platforms they're traversing, but kept the vertical rotation of the camera minimal enough that I was able to draw the assets with almost no distortion at all.
This is an abbreviated overview - for a detailed breakdown:
http://sglabs.schellgames.com/post/150450279423/building-a-25d-level-in-unity