On the one hand, there is no actual progression or ramping of difficulty in the game itself. The difficulty level remains the same whether your current score is 0 or 10 or 100. But every new highscore represents a new summit that the player has to scale. The first and maybe the most frustrating summit to scale is scoring a single point. To get your score into the double digits, the player has to have basic mastery of the core mechanics - including the precise physics, and timings- and learn how to handle a certain number of scenarios. The obstacles on the path to triple-digit territory and beyond seem almost self-imposed. The fear and tension as you approach your own highscore is the biggest impediment to breaking your highscore. Once you break that highscore - the hand tremors magically disappear the next time you approach it, only for it to re-appear as you near your new highscore.
All this, when the basic concept of the gameplay is deceptively simple. Like i said, there are many layers to unpack for someone who is willing to look into it.