I have yet to finish your game, but one a bit cold feedback before: if you expect the player to have all the collectibles at some point - PLEASE point it out close to the beginning of the game. I usually just go blindly and I got like 70%. I didn't want to go back at that point and look around again -.-
Another one like this, but here maybe i'm just stupid - I saw the first main boss area on map, and thought it was a blind corridor, and did not go there. Went there 10 minutes later after blindly looking around and suddenly BAM - boss xD Some shadowy fog would be a nice indication maybe. But it was just this one time, later I was expecting this.
I will finish it in few days, overall its very nice, the music make a nice atmosphere and I see that the main character is Samus in disguise;) My brain is broken from playing Volgarr the viking and I constantly throw spear with up button. Oh well ;)
I wanna see the implemented mushrooms;)