Great presentation. Very atmospheric, menacing, claustrophobic. Also addictive gameplay; I couldn't put it down until I beat Level 5!
I love the mechanic of having to fend off the enemies using potions, because it forced me to memorize some of the most common potions.
A couple of suggestions for improvement:
1) One issue I sometimes had is that the colors of the plants in the lower right are not as distinct as they could be, and I would use the wrong one because I had misread the recipe book.
2) Another issue that came up is that the ingredients overlap visually, and I often dropped the wrong leaf or powder in the flask.
A couple of bug I experienced:
1) After dying and restarting the level, I am never able to get a response out of the controls. I have to quit the app and re-launch, then load the save file in order to continue.
2) One time I beat a level while holding the red test tube. When the next level began, I couldn't put the red test tube down, or empty its contents into the flask. I had to reload the save file.