What do we see here:
I had this idea that I could easily combine 2D background with 3D characters and still use Unity’s NavMesh and NavMesh Agent without issue. So I built a quick prototype in which I was not going to use tiles, but a background that is distorted in order to render correctly through an orthographic camera at a 45 degree angle.

I wanted it to match up with the 3D items not just approximately, but as exactly as possible.

I brought in my trusty Nazi guinea-pig, my trusty biped and checkers.

So you see that 2 squares on the checker are 1 meter in 3dsmax and the box on the ground is 1 meter in Unity, but the background although a 2D images is rendered at a 45 degree angle.

I figure with this system I can make RPGs or even Turn Based Strategy games like Commandos.