This was a lot of fun. A full game loop, exciting gameplay and live multiplayer! Excellent execution of the concept, I hope you continue this project into a full game, I would definitely follow its development.
As mentioned before, some lifesteal skills would be awesome for the slicer, also would be fun if there were some more risky upgrades that would give you a strong boost but also a debuff to balance it, for example you deal more damage but you also take more damage
Overall this was super fun, it's amazing you've done this in 2 weeks along with all the documentation of the process, congrats and well done!