What I liked:
-Clearly a ton of effort was put into all of the art, because all of it was spot on, even the sandwich png just made sense
-UI functioned and was clear
-Cat!
-Lighting for the rooms had great attention to detail, specifically lighting and unlighting rooms as you went in and out of them
What I didn't like:
-No audio at all made me lose engagement, especially since getting kills, shooting or anything else provided no auditory satisfaction
-The enemies lacked variety other than the two types you had; it got very repetitive to face the same enemies over and over again
-The game tests your ability to mash the left click above anything else, which is not particularly interesting gameplay-wise since the dominant strategy is to turn your brain off and click as fast as possible without any downside other than physical discomfort
-As others have stated, the level 2 boss simply isn't fun
-The player feels sluggish compared to the average number of rooms expected to be traversed
-Taking damage was highly inconsistent; on several occasions enemies would simply bounce off of me, even if i didn't shoot them. The only time i died was the level 2 boss which is because i got swarmed on sight
-The medium health enemies are the same speed as you, meaning it is incredibly easy to kite them and take 0 damage
Overall, the art side is completely there, and the game is playable. The only issues are a lack of variety in the gameplay and a lack of audio of any kind. Both of those issues would drastically improve this game if fixed.