It is isometric, it's isometric top-down view and thanks.. :)
You can't just invent your own terminology. There is no such thing as top-down isometric. What you have created is a top-down view - nothing more. You have no Z projection for starters! Its a great little effect but its inaccurate to call your engine an Isometric Engine.
Below is a excerpt from Wikipedia..
The term "isometric" comes from the Greek for "equal measure", reflecting that the scale along each axis of the projection is the same (unlike some other forms of graphical projection).
An isometric view of an object can be obtained by choosing the viewing direction in a way that the angles between the projection of the x, y, and z axes are all the same, or 120?.