Agreed about the minimalistic graphics being nice. The floor randomly changing felt off. The way to avoid that would be to make a tileable floor so that you can spawn a new floor in immediately to the right of the one that's about to disappear. The same could be done for the background if you wanted to add parallax scrolling.

Game felt fine to play. The tail end of the paper airplane kept getting me as it juts upwards quite a lot. You can fly above the ceiling and go above the pipes, but you won't score any points, so there's not much point to it and it's hard to get back down. Hitting the floor moves the plane to the left by a few pixels which is probably a glitch.

Super cool, I really love the minimalist art style here. Only thing is that I would thicken the "drawing" lines a bit, sometimes (for me) it blended with the background...