Painfully hard, painfully addictive, however I'd recommend just a couple of gameplay changes:
Firstly have a quick restart button. Lets say hitting 'r' automatically restarts the game, regardless of where you are.
Secondly, try and reduce the 'black screen' time before the scoreboards pop up. If possible.
Thirdly, have perhaps the score/jump bar at the bottom 50% opacity grey rather than black, and have a clear line that shows "You cannot land on a platform below this line", as a few times I've landed on platforms I can't actually see anymore.