The unexpectedness factor is present at every time with the movement, the direction that the enemies goes and (maybe) the direction the player goes when is cornered and you don't press another direction.
I liked the music a lot, I just think the game was very slow. You have to wait the beat to move, which gets a bit slow at some point.
I liked that you move at one pace and the enemies at another. That makes you anxious (in a good way) and adds variety and strategy to the game.
Overall, nice job!
Obs.: the game is very heavy for a 2D game with simple graphics (but then I see it is made in UE4, so it explains a lot)