I doubt it would be orthogonal projection. That one is helpful in mathematics, as it literally "kills" one dimension. that'd mean you have absolutely no depth perception in your 2D image, but no distortion of the parallels either. Super Mario Bros is an example of orthogonal projection.
Zelda would be oblique (it preserves angles, not dimensions), but it is often referred to as "3/4 perspective", because we typically "shorten" the height dimensions: a tree that stands straight would look shorter on screen than the same tree lying on the ground.
The other *metric projections share the property that parallels remain parallels, but on-screen length for the same object vary depending on the direction it is pointing to. I guess artist don't like that too much because it means they can't flip sprites for left/right directions.
