I saw the update and gave it another go.
The last few boss stages I still found really difficult. 435 total deaths.... 175 or so of them in the boss room. I am not going to punish myself getting the remaining gold. All power-ups and the final cut scenes are enough of a win for me :)
Overall this was really, really well done, especially with using RPG Maker to create a platforming Metroidvania.
Feedback from my play through:
There were several times I felt the difficulty was quite brutal, even on easy mode. Some of the platforming just seemed a little random in terms of outcome, especially with the blue flames.
A little more guidance/hand-holding would perhaps be a little kinder to the player. There were multiple times I followed paths that I could not complete due to not having the required power-up, but did not know that. A power-up was gained in an area and it seemed like an area was accessible when it wasn't. I just thought I was terrible at platforming (well... still questionable on that!) when I just needed something to communicate to me that something was entirely not possible.
Remapping/swapping the controls for the menu and dash ability. It was just a little/lot clumsy feeling to suddenly have to adopt the C key, one over from the option menu, to dash. The amount of times I opened the option menu instead of dashing were many. That absolutely could just be my experience.
I primarily played the web version but also the downloadable. I didn't notice any difference/lag with control input performance, so I am thinking I am just not great at platforming.
There are some incredibly well executed concepts and ideas in this nicely polished Metroidvania, and I thank you for developing it.