Fear is subjective, tension is objective. - Some YouTube video.

I was watching a video [3:30] about how games (in this case Metroid Fusion) evoke emotion from the player - despite it just being a game.
Aided by sound effects, music, lighting, dialogue and story telling; our minds are synchronised with in-game character; and it’s pretty amazing to consider that it was all purpose-driven by the game creators.

Fear and Tension.

Fear is a subjective feeling. Your experience and environment aids you in whether you feel fear or not.
On the other hand, tension is an objective feeling; and affects everyone.

But the greater of these two feelings is when they are combined.
When tension disguises itself as fear, and convinces you to be fearful.

That utter feeling of helplessness, when you have knowledge but cannot do anything.

In terms of how this is actualised in the game, as the player you progressively get more and more powerful -
But you still are not strong enough to face off your doppelganger. You are put into a mindspace of powerlessness, isolation and danger, that despite your strength you have to run

Outside of the video game analysis; we can see alot of these ideas in reality as well.

When tension meets with fear, we truly panic.