Pong is by far, the great Psychological Horror game of all time. It's a game about isolation. You are stuck with only one other person in a never-ending loop. You can't really go anywhere or do anything meaningful, you must sit there and endure your situation. In that sense, Pong is a good metaphor for life.

Just like in the human psyche, your surroundings are black and white. When you're mostly alone, even your own opponent can be your greatest friend, which is why the background is faded out and black.

It shows you must accept your differences, because somebody is always keeping score. Even if the score never manifests in a meaningful change in your life, you still must pay attention to it.

In addition, the size of your character really shows how insignificant you are to the big and horrifying world around you. It's mind-bendingly scary. It shows how in life, everything is repetitive and your actions can never change that. Once you start you're immediately thrown into the cycle of knocking the ball back and forth, but you can never break the cycle, there's no option to quit, and no amount of score can make you advance, just like in life.

The darkness is forever looming, it is always present. It could swallow up everything you've known, but it doesn't because it doesn't think you're important enough, or perhaps it just doesn't care. This is perhaps the scariest thing about it. Nothing you does makes a difference.

Pong is for these reasons, the best Psychological Horror game of all time.