Nice little game! Some feedback:
I like the combination of blue and black you used. While we are at art though I think that the parallax is a bit too much. Lowering the background movement would be great. Also, was the infinite jump intentional? You said that that the dash was the only movement available, but it didn't really seem like the player was dashing. I think that adding some dash animation and perhaps a very small cooldown indicated by an UI element.
Still a very nice game!
I would also appreciate it if you could rate mine!