Hey really awesome! Vaguely similar concept to mine where you are the boss fighting against the hero, though yours is space themed and mine is more medieval/survivors like. I'm enjoying seeing these types of similar submissions!
Overall very cool. I loved the voice acting and the story going along with it. Character designs are also really cool. Also neat how you had five playable levels with a different ship to play as each time. Also kinda cool to have the "Hero" keep gaining the previous bosses powers. The whole thing is very well done, especially in only 48 hours!
A few minor feedback items just in case you are curious:
1. The dialogue was cool! But they did seem a little long. I think it was more there was sometimes a second or two delay between each line of dialogue, but it did seem to add up.
2. The fights were a bit long as well. I won each one on my first try, but a couple of them were very close and wasn't sure if I would have tried them again if I had lost. I wonder if halving the health for both Hero/Boss may make the damage feel more impactful while also not making the fights too long or an annoyance to play through again if you lose.
3. I couldn't figure out how the red laser worked. Eventually it usually just kept hit the Hero, but was a bit confusing and felt kinda like luck to me.
Still though super great! I also really enjoyed the twists at the end. Great job with this and good luck!!