I like the approach on the theme by giving you the ability to play "both" sides.
What I did not like so much was that I had trouble traversing the level and that's why mostly rushed through without killing anything. After I was put into the different perspective all humans were already dead so I was not actually killing anything but yet I was the bad one for killing everyone.
I think a "pacifist" ending would have done the game good.
I was also missing sound effects and music to set the szene proper. Only the dialog sound was there when I played it.
Nonetheless you finished the game in time. You have a story and you have put a lot of work into it while still using only the colors provided for the jam. Your flames were well done and I had to look twice to see if they are part of the palette.
One last suggestion: While in hell your character is slow and does not jump very high. While alive you are racing and jump like crazy. Maybe adjust both to the same values and meet them in the middle.