I made it to the second hearthstone cave without killing anybody, despite the game's attempts to get me to murder everyone I met at every opportunity, but at that point you can no longer progress in the game without killing (all quests require murder). Oh well.
What an insightful game. The seed knew all along it was an acorn, but it had to pretend to be many other things along the way to satisfy the world, until finally it was able to be what it always was.
Holding the jump button should make me jump higher (tapping should make me jump lower). Also, holding should NOT make me jump when I land, especially if it's going to make me flutter-jump. Crappy controls, did not finish, 1/5
5/5 would play again
Vlad - That's what the "Stats" screen is for. You're probably missing the "attack" where the boss changes which side of the screen it's on. Difficulty doesn't matter so if you want the secret play Easy for a while to nab that last attack.
Darkruler: Every attack is avoidable. If you have the secret, you can easily see the hitboxes of yourself (not your entire ship is vulnerable) and enemy bullets (not all of the bullet is dangerous).