Nice game, with a good and satisfying game feel already implemented, and what feels like a solid gameplay loop built around it.

Here are a couple of suggestions that could help you if you want to work on the game more:

1. Add a way to clearly see where you are aiming: since your sword points in a different direction than the direction you are facing, it may be cool to instead have a way of understanding where your character is pointing (I initially thought the point direction of my mouse was wrong because I was looking at where my sword was pointing).
2. Make the start of new waves maybe triggered by the player instead of having to wait for a delay, so that the player can always decide to immediately start the next wave or maybe take a little break before doing so;
3. Add a clear feedback for when your character gets hit: the feedback from the slice of your sword is already nice, maybe doing something similar for your character too other than having the screen flash red could be a nice touch :)
4. I don't know if this is a bug or its intentional, but every time the boss lands, I instantly die... That's obvioulsly not something you want, since it feels like winning or losing is out of the player's control with a random, unexpected instant death mechanic.
5. Polish the game a bit with animations (especially adding some animations for the main character), on pair with the quality of some animations which are already implemented, like the reverse kinematic animation of the crawling enemies which look very cool.

The gameplay is fun, and even though I don't think it belongs in this jam since I can't really see the expansion theme being explored in the game, I think, if developed and implemented further, It may become a good commercial game too if you believe in it :)

Gameplay is really fun and is overall quite polished! Love how the enemies move and attack in this game.

Though I'm not seeing much of the expansion theme over here, there's supposedly a mechanic where the boss kills you and it "expands" but I don't quite get it or get to see it in action. That probably doesn't matter though since your goal is to upload and showcase the game and you did it!

Combat design is very good

Well, the page says you submitted 5 minutes, 27 seconds before the deadline. So you deserve a review and rating.
I like the art style, and that mechanic of progressive upgrades and trying time after time to defeat that damn red flower is so cool! At the start it's very slow but in time it gets great!

Nice flowers, mate! ;>