I got to the end of the third level until I killed the boss but the stage didn't end. I think it might've been a bug.
The game has lots of really nice particle effects and cool designs, and I really like how the UI sort of has a warped perspective. It's nice how it had a little prologue cutscene to portray the story too. However (and this is probably an unpopular opinion), I think the game visuals have TOO much red. Like, I get it's the point of the plot, but combined with the high abundance of bloom, it just makes my eyes sore after looking at the game for too long.
In terms of the gameplay, I find the 2.5D perspective really awkward. It might just be a me problem because I don't think I've played a shooter with this kind of perspective before (only melee beat-em-ups), but it makes aiming at enemies a pain - it's very difficult to tell when enemies are in your line of sight (and vice versa for when enemies shoot at you). Perhaps have more leeway with the hitboxes to remedy this. I think the fire rate is too slow, which adds to the frustration when you shoot and your shot misses. It may be more satisfying if you had a more rapid fire, or if you could hold down the shoot button to repeatedly fire. It's definitely a unique take on a platformer shooter though, I think it just needs some work to get it to feel right.
The green tentacle enemies were the worst, because they almost never gave you an opening to attack without getting hit, and whenever they did you might miss your shot anyway because of the awkward perspective (this flaw is enhanced when you've got two green enemies right next to each other firing at at the same time lol).
In my opinion the levels were too long and repetitive. I just wanted to get to the bosses so It ran through most of the enemy waves and tanked their attacks because I couldn't be bothered to fight them with the gameplay flaws, it was too annoying. Maybe have an additional 'boss rush' mode that's more typical, where it gets rid of the regular parts of the levels and just pits you against the fun bosses (this is something I realised with my jam entry, so I added it as a late addition).
The music was alright and fits well, but it got really repetitive since it's the only track that plays.
I also didn't know if there was a use for the self destruction, it seems like an unnecessary feature for your game (even though I understand it was part of the jam theme, but imo i think it's better to just leave it out if it doesn't have a place in the game instead of forcing it in).
Also I think the way that the score keeps constantly increasing can be abused to get high scores by camping when there are no enemies around.
Overall, pretty cool graphics, but I think the gameplay needs some tweaking. Nice work!