Remarkable: The completeness of the game loop design - the fact that you've got a "waves" system.
Needs Improvement: Objects and environment felt a little random (i.e. not the most believable environment). Also, it felt like it needed more sound effects to help the player locate the covid spheres. Not that it was "too hard", more that since you added the gun sound effect, it raises the level of expectation that this game world makes sounds and so other things should be making sounds also.
Successful: Even if the world is somewhat random, the threatening feeling of the enemies/waves definitely works.