Wow, this game is so fun! Somehow it's just so satisfying to slice them.
I like the concept of the enemies becoming stronger together instead of the player.
I really like how the music starts out calm, and changes to become more fast-paced when the first stage 5 cell appears, It fits how you feel when playing the game. The virus animations are also very smooth.
It also has a nice feel of simplicity, it's very easy to get the hang of but still super fun.
My only suggestion might be to make it so that the player is constantly slicing, as my hand quickly gets tired from holding down the mouse button.