Very good game! I didn't expect a free game to be this large or high quality.
A bit of feedback though:
I felt a lot of the time that the most effective way to play the game was to "cheese" it, for example by sniping enemies from a distance, tanking or jumping over them rather than fighting. I personally found this kind of fun anyway, but it's maybe not what you intended for most of the game lol. That being said I'm not sure how you would entirely fix that, since it's sort of endemic to how the whole game functions and other people seem to enjoy the core gameplay as it is too.
I think to improve this you could rebalance a few combat mechanics, mainly the massive difference between the strength of weapons;
When I first tested out the bombs on enemies and saw how much damage they dealt I thought to myself, there's no way you can design an effective boss now if you want players to be able to use other weapons as well. And indeed when I got the final boss I was able to beat them by standing in the corner and throwing bombs before they got through even half of my total health. The persistent damage idea is nice, but I feel like the bomb needs to be nerfed as it trivialises every boss encounter after. Not to mention that you no longer have to engage with ground-level enemies because all of the can be easily one-shot.
I also found the sword much weaker than the gun, which feels wrong because so much of the enemy and boss design is built around the sword that I feel like it isn't meant to be outclassed. The verticality of the sword hitbox was sort of weird, and the animation was really slow. Plus I don't think the stamina restriction on guns is enough as it stands - For regular enemies you can run away and recharge your stamina, and in bosses you won't be attacking all the time so in that time you can wait for it to come back (which happens very quickly). In fact I personally found you can get significantly more hits off with the gun than the sword, because you don't need to worry about setting up the right spacing, and at the same time you have way less risk.
This wouldn't be so bad if stamina was used all the time for movement, but the two moves that use stamina aren't that common and again both suffer from really slow animations.
This was why I didn't use the backdash very much; the tutorial prompt said to use it against the snakes, but whenever I hit them I would get immediately hit back before the backdash had time to activate. Maybe I wasn't using it right but it seemed kind of useless. This in turn made the sword less useful, because the sword and the backdash complement each other.
I also would've preffered it if the i-frame dash was faster, because it lends it more use and I always feel the dodge-roll/i-dash is the best movement tool in any game that has.
Another change could be to have more late game enemies and bosses should deal double or triple damage, because your health grows much faster than the difficulty, which encourages tanking as the game progresses (I didn't really care whether enemies hit me by the time I was in the final area)
That being said, all the other components of the game were so strong that I didn't mind too much overall and still really enjoyed the game.
It would be cool if there was a true ending update in the works because the way you've set up the story seems to be leading up to that, especially with the dialogue from the man with the dogs. Unless there already is and I just can't find it :D