What’s the name for this 3D scene style from a fixed angle?

Two relevant terms:

• The type of flat-3D perspective is isometric view (or more accurately pseudo-isometric because it looks like it’s not strictly based on 120 degrees).
• The style of limited-detail but accurate drawing is like instructional diagrams – in particular, it looks based on styles commonly used in in-flight safety diagrams. A lot of the incidental graphics in Portal and Portal 2 reference styles used in corporate instructional diagrams.