I love that bubble explosion animation in FPS mode.
In terms of gameplay, as others have said, increasing enemy difficulty would be nice; but in terms of Art Game About Proper Pandemic Procedures, it really struck me how easily the viruses could be held back with one upgraded sanitizer and proper social distancing - and how quickly the infection got out of control if the social distance wasn't there.
(By the way, I experienced the same bugs as others did - both the cash bug and the negative enemy numbers.)