Wow, this really blew me away! This game had so many layers to it that made it such an exciting journey to get through it all: to be honest, I think the shooting gameplay by itself would've already been enough for me to call this great (super fun abilities to use, tons of cool enemies and bosses with varied moves, great levels and enemy formations to contend with, etc), but to have everything else on top of that was a real treat. I loved all of the little touches within the game that made it ooze so much charm and attention to detail, like the fact that the DOS prompt accepts other commands like DIR, and the way the game changes to reflect Gargul's taunts, and so on.
If I were to have any complaints, it would be that the rhythm gameplay felt a little sketchy/patchwork and out-of-sync with the music (though it was just a throwaway gag so it's forgivable) and that for me, personally, it kinda suffered from the SUPERHOT issue where I just wanted everyone to shut the hell up about their weird story that doesn't make sense and stop interrupting me from playing the damn game! Haha, I do like the story though, and hopefully you can just take that as a compliment to how addictive and fun your shooting gameplay was!