Really enjoyed this! The first thing I thought of as I was reading the premise was the player will be experiencing hallucinations, or something along the lines of that, in the gameplay to make it more difficult, so I was a bit disappointed. I do have to admit I only reached wave 10 so maybe the interesting parts are further down?
However, I did enjoy the rest of the gameplay, the usage of the sound effect and also the art too. Good job on this!