Great game!
I love the art style and the fluid and fast movement. Reminds me of the good old Quake days.
Using and upgradable stick is a pretty nice idea. Especially because you can stack multiple addons to the stick. First I got another stick that made the the weapon look like a cross and then I got a Sword and shortly after the magic orb which is my favorite and made it rather easy to kill the gate keeper. I think this is great. If you want more of a challenge grab only the stick or the sword. If you need it easier and want to keep distance grab the orb. I like the variety of how I can solve "kill the gate keeper" problem.
The map was rather large but did not feel boring. Moving fast help a lot with that. I had some trouble finding the boss again after I had to run away for a while. I would not add a map but maybe a marker or some compass marking pointing towards the gate would be nice.
On minor thing that annoyed me a bit but is of course a personal preference: I could not invert the mouse. Other than that it was very enjoyable
It's really awesome what you did in 10 days! Well done!