Woah this is some really good stuff! I love the art
-A restart button
-Having the character flash during invincibility frames would help me better understand how long the I-frames are
-I personally would recommend removing the Godot loading screen
-The second phase attacks are very easy to dodge so maybe they should be centered around the towers or something
-Explain what the highscore is, maybe have it be part of the in game UI. Personally I think replacing the Highscore with a "lowest time" feature would be nice
-Finally, I think bigger attack with more time to dodge could help shake things up. Maybe those attacks could do more damage too
Edit:
After trying the other characters I have another thought. Something that you may not have realized is that having a slower fire rate makes a gun better. This is because firing slows you movement so firing less is ideal. If you want characters to feel more balanced (which you may not, you might want some to be more difficult) then I'd give the slower fire rate characters some other nerf like slower movement speed in general or low range.
Also it's pretty fun to hit both the shrines with Paradox's gun at once but MAN does it feel OP lol
Edit 2:
I hear a low buzzing in my left headphone when the music plays, feels weird
Edit 3:
I noticed when playing as Abrams that his hitbox goes to the top of his head, this feels unfair because if we imagine the battle in 3D space that wouldn't've hit him if you get what I mean. I'd make the hitboxes be a circle around the character's feet instead of covering their whole bodies because of this