Game worlds are viewed from a camera, which is the viewpoint from which the game world is observed from.
The camera is what dictates what is shown on the screen, whether or not it simulates the effect of a video camera. It can depict an invisible viewport of the world around the player character, or it could even be showing things as if from the perspective of a character.
Questions under the purview of this tag generally deal with camera positioning, movement, and special effects.
When designing a 3D game, you might also want to take lighting into account when appropriate.