In some games or game genres, a typical 3d perspective camera projection does not really work. For example, classic 2d platformers (2d by definition does not have a perspective) or top-down shooters. And since UE4 is a 3D engine in the first place, one gets a question: how to implement an orthographic camera in UE4?
Orthographic camera
Fortunately, Unreal Engine has an option for such camera mode. You can enable it in Camera Settings for a Camera Actor: