The care you've given to eek out the most of the restrained visuals is especially nice.
Your take on the theme is quite compelling but I'd have liked to have seen more attention given to the scoring system as you could have leaned into the idle nature of the more so in that regard.
Overall I like the visual style you went for and minimalistic flare. I'd like to see this vision fleshed out further and could see it doing well given how near to the vampire survivors trend it leans. Unreal did bloat out the file size though given how minimalistic the experience is, 200MB for this is asking a little much but thats just nitpicking. Consider using a leaner engine next time if your vision doesn't call for the might that is Unreal - could be a fun opportunity to learn something like Godot or Unity which would have done that in <10MB & been able to deploy to web.