(I am now in a rush to test as many games as possible to help, so please do not mind the cursory reviewing style.)

controls are QWERTY-only instead of layout-independent, BUT arrow keys are enabled

as per TheLastMage, maybe make the player faster? OR not if you do the following

Suggestion: for the moment, we do not know which direction the cube is going to choose to rotate; I think putting an indication at the last moment would put the reflexes of the player to the test in a pleasant way! :) Something like a shiny ‘RIGHT!’ in the top or bottom middle.

Concept looks promising! Too bad you only had less than three hours, but it is precisely great to have come up with this in such a short time. Necessity is the mother of invention. ;)

It could easily be a flappy-bird like game. I suggest you to give more time to play test the game, because the movement speed for the player character is slow as hell compared to the fraction of the second I have to dodge the golden cylinders. Add some SFX, rework the look of the game, and you have a cool minigame.