Emphasis refers to the size relationship of elements versus each other, and vs. the world as a whole.

 Balance is a result of the fact that the player’s eye will unconsciously use the middle of the screen as a fulcrum, a center point of the left and right side

Economy is a level in a video game is typically filled with movement, VFX, sounds, and maybe a little too frequently someone trying to shoot you.

The environmental focal point of a location is called proportion.

 Elements and principles of design provide a tool set to the artist which images can be constructed.

The relationship between all the separate elements of a scene or level is called direction.

 Unity is used to emphasize depth and the scale of a location or area.

Rhythm refers to repeating occurrence of visual elements.