There's a difference, I think, between a game that is hard to master and a game that is hard to control. I also finished in just under 20 mins with 349 deaths, but sections of this are made painful by the level of precision that is required from floaty controls, ungenerous hitboxes and the weird effect of ceiling collision. The design challenge of making a hard game is how to make its difficulty fair so that improvement is meaningfully differentiated from luck.