I like the idea of this game, but the execution is a bit lacking.
The mechanics are pretty simple, and I was able to grasp what I was supposed to do when playing the tutorial, however, I was confused by what I was supposed to do when faced with those long white rectangles as it wasn't mentioned in the tutorial.
Furthermore, I'd have to agree that the levels are too difficult, and it sucks there's no way to lower the difficulty. Although this game is hard, it's also as equally lenient. I was able to complete Red without dying as I healed by staying still. While this mechanic does make the game easier, it doesn't make it enjoyable.
There's nothing wrong with making a game, hard, it's just that given the odd controls (which is made up for by the fact we can change them as we please) and while the game looks good visually, the colors of the obstacles don't stand out so it's very easy (for me, at least) to get overwhelmed and not be able to react fast enough,
It'd greatly improve the game if you added different difficulty settings where the blocks get gradually faster (the current settings should be set in "Hard Mode" in my opinion) or maybe make the blocks move slower or not fill the screen with them or make it we don't have to dash to the complete opposite side of the screen to avoid taking a hit. And making important things like the controls and obstacles to dodge stand out a bit more so people can see them.
Hard games are nice, but if there's no chance to get better by doing something easier, the fun is lost very fast as well as any interest in playing the game.
TL; DR: Interesting idea for a game, however, it's too hard to play given the fact that it's hard to see the obstacles and there isn't much time for players to react. Also, kind of a nitpick, but I found it a little hard to see the text at the bottom given the color.