That was pretty good, and with lots of screens to explore! The idea of having Juni run through the background was brilliant. I also liked the "glass tint" effect in the firewatch tower and the detailed backgrounds in the grey forest area.

I did find quite a few SGEs and inconsistencies here and there, though. I assume some of them are due to the tilesets not having appropriate tiles for thin ledges, but I also spotted non-matching background tiles in the grey forest area (e.g. x1024y985 has both grey and black tiles mixed up) and floors/walls with missing borders (the ground on the left in your screenshot). Also, it felt very weird meeting normal-sized creatures and knytts while still running through the background. I think these could be replaced with simple scaled-down tiles instead of fully animated OCOs.

Other minor issues I ran into:

* x1035y981: It's possible to become stuck on the small area to the right of the artifact if you don't have the climb power-up at that moment. I had to resort to pressing CTRL+R to get out.

* x1027y981: The ground isn't at the same height as the screen to the left. It's not a big deal, though, since this doesn't trigger a wallswim.

Nice level, though the ending was abrupt (in addition to what sergio and VG said)