If you've seen a few suspense movies, you know the story will unfold. A scary unknown interrupts the comfortable world and induces panic. Then the "good guy" steps in and at first appears to be in over his head trying to fight the evil. But in the end he overcomes the "bad guy" and restores normalcy to every-day life.
The movie is fun while it lasts, but you can't watch it more than a few times before it bores you.
NHL hockey is similar to a suspense movie, but better. Much better.
A hockey game has its scary moments. An opponent deflects a shot just wide of your team's net. One of your guys gets laid out and doesn't get up for several minutes. An opponent gets an excellent scoring chance.
An opponent scores a goal, at which point you might start to worry if your team will lose that night. These things happen many times in every game (the first and third examples, at least).
But unlike in suspense movies; when the story is planned out, you don't know what will happen. The future result of the game is a mystery. The players don't have choreographed moves to execute. Instead they make countless decisions on-the-fly in every game. That's called improvisation.
The unpredictable nature of NHL hockey makes it the perfect improvisational thriller.