Interesting demo! Loved the main menu screen and the designs of the protagonist and the boss, though everything else felt very unfinished.
Jumping and dashing are very floaty and it feels like you have very little control over your air speed, making it easy to overshoot or undershoot platforms. The E key (to pick up the needle upgrade) and Right-click (to shoot) are required to progress, but it isn't said anywhere in the game or on the page and I had to find it through trial and error.
The hitboxes for the player attack and the enemies feel a bit unfair, you have to stand so close that it's hard to avoid damage yourself, and your basic swing only seems to hit enemies in front of you despite looking like the character swings above their head. After a while, I just started running past all the enemies.
In the end I managed to find what looked like a boss, but couldn't get past the door to his room. However, I still managed to kill him through the door. Based on how many hits it took, I think his HP was way too high to fight him legitimately! On the other hand, the music was very nice when it played. Overall, definitely needs a lot of work, but good job getting the demo out!