Nice little game, the music is a BANGER
I love the SCP part behind it, nice idea, and nice way to implement the theme, tho it could have been tied to the gameplay more.
I have some issues concerning the audio mix tho, but nothing too bad.
First of all the overall volume is way too loud, it scared the hell out of me when I launched the game haha. But it was nice to have the option to lower it in the main menu :)
And the other issue is that when several enemies of the same type shoot together, they shoot in the same rythm, and they all have the exact same shooting sound that plays at the same time, so it's very loud. You can fix this by making them shoot out of sync, and creating different variations of the bullet sound (with different pitch for example) and randomize the one that is played each time an enemy shoots.
But, overall, it's pretty nice, keep it up! ;)