Really well done. The visuals are interesting and different, and the concept of the light and shadows works well as a gameplay mechanic.
By far the most interesting, and distinct, concept is being unable to bank your essences between days. The other comment complained about this, but I really feel like it sets this game apart, and makes progression require either skill, or careful skill selection, rather than just "rinse and repeat" until you get enough to buy some expensive upgrade. Having to stay alive long enough to reach certain essence requirements adds a lot to the feel of progression. Remove that, and it's just grinding.
I like the introduction of new enemies as a consequence of unlocking pieces of the skill tree.
My only real complaint is that there are times I just have no idea where the Essence of Light is on the map, usually when it spawns way off in a corner. I kept thinking there must me something I was missing in terms of being able to track the essences when I couldn't quickly find them. It's not very fun to feel like I've checked the whole map, and still not finding an essence, because it was so far off in a corner. Perhaps some approach to showing the direction to the next essence would make sense, perhaps only if it's been sitting there for long enough?
And a couple of minor things you might improve:
- Every time the skill tree opens, the middle item pops up, and I need to hover it to get it to go away. Maybe just a bug.
- I don't know why the magician asks if I want to create a new soul when I don't have enough to create one.