As promised, ill had a look at your game.
When I opened the game these things came to my mind. I would have liked if the game did start with a very very low volume instead of the full blown volume music. Chiptune music is quite hard on your ears at that volume, so I would have liked to change that. The volume slider could have also been in the main menu instead to directly tweak it, it could be in all menus if you still want it in the level select. It was weird that the music didnt loop, so while writing this, I could not know what the correct volume for me is. The choice for soundeffects is good, they fit the rest of the game and aesthetic of the game. The sprites also work out pretty well.
For the tutorial, sequencing the individual steps would work better. I was overwhelmed with the amount of information that I was presented with. Also the white text blends in with the Health text underneath it.
The first time I played it was not clear where the game starts so I placed the towers at the wrong spot (the end instead of the beginning). The programming aspects of towers also was not explained at all to me so the first time I had just towers shooting at nothing.
Quite frankly, I had not fun playing the game. It was very tedious arranging turrets, it felt more confusing and frustrating than it felt fun. I am also a programmer, so I have background knowledge. Anyone without basic coding knowledges will not understand the looping mechanic. I could not even beat the first level after 3 attempts, I gave up and ragequitted initially.
I feel like the gameplay loop needs refinement. If you want to stick to the programming loop, it needs to be much clearer what the individual actions do. I also think a more generalized programming for your round could be more interesting. For me the game felt like an unnecessarily complicated tower defense game, where the twist or spin didnt feel rewarding at all. It did not feel like I got something from being smart with my programming or tower placement. I had no agency. Tower positions were predefined by you, so I couldnt try out more creative solutions. When retrying this became very apparent as there was most certainly a dominant strategy, I couldnt find it yet tho. The tesla coil felt incredibly overpowered. I soloed stage 2 and stage 3 with it as you had enough HP to just ignore the fire spirits. Generally I could mostly ignore special enemies as the HP pool is so high. The auto turret felt very buggy, the aiming made no sense and it often perma missed unfortunately.
I feel like the player should be able to place turrets anywhere to give them more agency, to make it more interesting. Yes I am aware this is a gamejam game and its a very decent entry considering time, but that is what I think youre missing. Give the player more control over the game. Give them the possibility to influence the outcome more. I want to place turrets in dumb spots because i want to code this really stupid loop for my turrets. I appreciate handholding initially but afterwards I want to just do my mistakes.
Hope this feedback can help you.
Edit: I hope you can understand that the way I wrote is mostly because I am German. I still think its great that you pulled off such a game is such a short timespan. Its just the way we Germans are with feedback haha. Gl on your gamedev journey.