Wow, I've enjoyed this very much.
This is a proof that you don't need AAA graphics to get immersed into the gameplay.
That being said, there's only one thing that needs refinement and that's user controls. Two things in particular. The horizontal acceleration feels too high, almost completely unpredictable. And the other thing is getting stuck to the wall, when a corresponding arrow (towards the wall) is pressed. Almost as if the gravity no longer applies.
But other than a few tweaks for user controls, this game is really fun.