Uploading, of all things, a .7z of your game is going to make it less accessible to people. Not everyone has 7zip, after all, and not many people are going to download it just to play this game. That was my first impression—"Weird file format."
My second impression was realizing too late that I was falling into the black hole while reading the boss's explanation of how to play the game (and not fall into the black hole). My third impression was that the ship controls were awfully slippery, but they grew on me as I got used to them.
My fourth impression, if I had to number it, was how the game's individual assets don't really cooperate aesthetically. The sprites look fine, the background looks fine, the black hole looks cool, but none of them seem like they were made in quite the same style. The most obvious dissonance is between the player ship and the boss ship, one of which was very obviously a small sprite scaled up.
At the end of the day, it's a simple game. I could nitpick things like how you can't dismiss the boss's last message or how underwhelming the lack of even a victory splash screen is, but this is a game jam game; it's fine. It would be neat to see what else could be done with this kind of spaceship game.