What I liked:
- The simplistic pixel art; A bit Atari like
- Pygame!!
- The ambience. Good choice of music and sounds effects
What I didn't like:
- The tutorial. Text walls are really not good and are more confusing than helping
- the bottom UI was took too much of the limited vertical space
It is impressive that you've done all of this in this short amount of time without an game engine as most of the game feels good (The entity movement with scrolling background, Movement, etc) but maybe you should plan in more time for making a good tutorial as it's key for people understanding your game.
btw to my knowledge a few weird anti virus programs flag pygame as a virus.