Could someone tell me what this projection is called?
It's as if you are looking at an object from directly above it and then smear it up and left equally. Only the one dimension seems to be true scale while the other two are skewed.
I'm not finding many games that uses this style, but some of the Ultima Series seemed to or at least something similar:
That's an Oblique Projection.
Oblique is a type of parallel projection where the projection "rays" are not perpendicular to the image plane.
Usually this is used to show two spatial axes perpendicular & without foreshortening (as though looking directly down the third axis), while the third axis is splayed off at a diagonal. In an orthographic projection, this third axis would be invisible because we're looking at it edge-on.
Depending on the amount of foreshortening on the diagonal axis we might call it a more specialized name:
Note that both of these projection titles are used most commonly with the front or side of an object presented undistorted, with the depth axis skewed. In your case, it's the top view that's undistorded, with the height axis skewed. The principle is still the same though.
Further reading, including examples of additional games using oblique projections.
