A lovely distinct visual style, and a unique core concept that I think has a TON of potential.
I can see so much open design space surrounding the levels, for example, using the mech as a mobile platform to reach new areas, or adding new ways to spend essence. Typical metroid-vania progression elements would fit right in (such as new weapons and abilities that open up the map more).
The basic combat of the mech had a good rhythm to it. The pilot's attack was too stationary, and felt slow/unresponsive though.
The main issue was the frame-rate. This game was maxing out my GPU, and going down to ~15 FPS (rough guess). Some audio would also be nice.