Excellent improvements.
I like the swarm of attackers. Good idea. Making that optional a very good idea for players unable to deal with the pressure. On that front...
...to really bump up the accessibility of the game for users with very slow reactions, you might want to also add a difficulty slider for the black-hole frequency, from none to what you have now.
High-contrast mode a nice option (maybe use the TV contrast symbol for that. I would suggest that your space ship should be more prominent in high-contrast. If I blur my eyes, I find it hard to work out where my craft is.
Still think it would be good to have a sound effect for when you press SPACE BAR/Left-click. Even if just a gentle blip. Helps understanding.
I still think the master volume is unnecessary clutter.
Nice!