Pretty fun game! The mechanics are straightforward, and it feels rewarding whenever I beat a level. I could see this being a fun arcade-like game!
If I could give a few pointers on where this could be improved, I would like to start with the control scheme. It felt clunky bouncing between the number keys as well as holding down the shift key with my pinky because the walking speed doesn't do much. Overtime, my hand started to ache. It would've been nice to use the scroll wheel on the mouse to cycle between the potions as well as tweak the walking speed of the character. Also, it would've been nice if the potions also broke whenever they collided with the enemies. There were moments where I threw a potion and watched it bounce off of a giant monster, and I found that unfair.
One other thing, I can see the alchemy theme in the game, but I don't really see "shadows".
Considering that y'all made this in train rides to and from work, I say y'all did pretty well! Keep up the great work!