This game is great!
The visual is pretty cool, sound, theme, etc. everything are perfectly fine!
However here's my opinion:
I don't have any trouble with the difficulties, the boss isn't that hard anyway, I already memorized her attack pattern after a few tries, what's makes this game seem hard are something else entirely.
First it's just probably me, but I never ever used my pinky finger to push a button, which is why it felt too awkward for me to press Left Shift with my pinky finger to dodge, usually movement and action button were placed in a separately like WASD for move and HJK for attack dodge etc. it's done that way so both hand can focus on their respective roles.
Of course there's an action button near the movement button in the console controllers like L1/L2 but you know that's because only one finger are focused for a movement so there's free finger which can be focused on something else like additional action but on keyboard WASD you need 3 finger to standby on it.
*For improvement, you can add an option which allows player to configure the control, most of game usually had this feature but um yeah you probably didn't have enough time for it due to jam being just a month.
Now I'll move to the right hand, Attack and Rapid Attack work just fine, what don't sit well with me is camera, I need to swing my mouse around whenever the boss jump to my blindside, and you know that the boss not gonna wait me to set my camera and ruthlessly attack me, so I have to run away every time she jump behind me to gain a distance and set my camera which is pointless because her shockwave attack will catch me in no time LoL.
*For improvement, you can have camera to lock on boss, or you set a button like Q or E to make the player quickly rotate 180° or 90° to left/right, that's your choice or maybe you just want to keep the camera that way to increase the difficulty? well that's fine too I guess.
Before we continue, here's my gameplay experience:
1st try, I'm having a skill issue because I had no idea what the control is, I thought the Space/Shift Key was attack since it was what shown in the menu, so yeah I died in the most pathetic way you can imagine, to avoid any slander, I did looking the game page but there's no mention of Control, there no ReadMe.txt in the game folder either which is why I thought there will be some sort of tutorial but I was greeted by the boss right away.
2nd try, I found the control and it's located in the Option, I don't know about others but the first thing I do on a new game is selecting Game Start, the only times I opened the Option first before Starting Game is either because the Sound is too loud for no reason or the game screen is too bright/dark, anyway I know the control now but I'm still dying because my dodge timing are very off due to my pinky finger did sync pretty well.
3rd try, Since I can't dodge anyway, I tried to do a battle of attrition and obviously I was defeated again because I died from just around 4 hit I think? while the boss HP like 200% something LoL.
4th try, I realized rapid attack are useless for me as the boss alwy counter me right away with a whirlwind kick or something.
5th try, I don't use rapid attack or dodge at this point but the boss still beat me with shockwave when I was trying to gain some distance to fix my camera.
6th try, I'm furious so I just trying to move around without attacking the boss and analyze her attack pattern behavior, I took all of her attack from Close distance, Mid distance, and Long distance, then died.
7th try, I brought her down on her knees with just basic attack, and movement without moving camera, that's it.
After that I was getting ready for the next battle but... Nothing Happens, I already walked around the map and I didn't find anything else so I don't know is it bug or this game only has this one boss.
*I can't really say anything about the gameplay because I probably played it wrong way, I didn't use dodge or perfect dodge, rapid attack, or attack window something but at least I'm sure that instructions for game like controls, or how to play are needed like you can put it in your game page or in a ReadMe.txt or at least make a tutorial in game which explains how to play to avoid first blood in vain.
Anyway I can't really say this is a boss rush because... I just encountered one boss unless I missed something, then again... I know making 3D model might time consuming, not to mention animating them so I guess it can't be helped.
*Actually I had few improvement in mind like parry, special attacks, weaponry, and other stuffs, but I think you can figure something like that yourself.
Oh well, don't take my words to the heart, instead use it to improve your game making skills, who knows someday you can make a game like Metal Gear Solid or something.
That's all I guess, if I write something wrong or missed something, let me know.
Also your game hold my cursor hostage and I can't open Screen Capture so I ended up using my phone camera, I know there's a short cut for it but I forgot and too lazy to look for it.