I made it to the last level at which point I had to sometimes switch browser tabs. The game lagged and so I lost my progress.
Anyway, the game is quite entertaining and very challenging but it seems that the big part of the challenge comes from extremely counter-intuitive controls. This type of games is best played with gamepad, but leaving that aside, normally left hand is doing character movement using WASD+Space (to jump) and right hand does all the actions. In this game this is swapped.
Please, fix the controls:)