This is a very fun game and I love the overall aesthetic! I do have some critiques though, one of which are my bullets having a 50/50 chance of doing any damage to Siren Head even though I hit him square in the chest. My other critiques pretty much echo the other commenters regarding the general bugginess. One last thing is perhaps include checkpoints? I have yet to get past the watch tower without getting killed and having to retrace my previous steps over and over is taking some of the fun out of it. That and I don't like that Siren Head can reach through the watch tower like he's intangible to grab you from inside. He's difficult and scary enough without that additional superpower lol.
Anyway, I think this is a good game with a lot of potential. If the aforementioned critiques are addressed (at least some of them) then that would elevate this from good to great. :)