Never played Castlevania 64 myself, but aaah this still brought me right back to me childhood playing N64 games. I can imagine myself putting this cartridge into my N64 and playing this on clunky CRT. Really nailed that feeling. Maybe except for the menus (Relatable though, making menu assets isn't my cup of tea lol)
Relatedly, since I was playing with a gamepad, it felt confusing that the title screen required the mouse. Made me almost second guess myself, like "I know it says I can use gamepad but can I really?" Guessing not having the menu controllable with buttons was just a matter of time.
I love burst movement, so the kickslide/butt wallop went pretty far in making me like moving around. The jump was a little awkward though. Mostly just because the arc is so tall on top of it being static and gravity being pretty low, so jumping will always leave you in the air for a significant amount of time. I believe Castlevania 64 has variable jump height, though I could be wrong. Haven't played it myself, like I said. That said I love that the slide will interrupt your initial upward momentum from jumping, which somewhat makes up for the lack of variable jump height. That felt really good, like jumping and diving in Mario 64. I would say that the slide having as much cooldown as it does is a problem, but I understand that having the player be able to move too fast would throw the balance out of wack. It's already somewhat possible run passed everything as is.
I'm assuming this is already known, but essentially jumping has an infinite buffer. So if you are in a state where you can't jump, say in the air, and you input jump, then the game will make you jump as soon as it's able to. Like I said, though, this buffer is infinite. So, say you just press jump twice in succession. You'll jump like you wanted, then when you reach the ground again you'll immediately jump again. This buffer seems to exists for any state in which you can't jump, so it happens if you try jumping during a kickslide, for example. This didn't get in the way too much, but did lead to a few flubs.
Attacking didn't feel quite as good as moving, however. I think giving Reimu's attack some feedback with sfx when she does the attack and another sfx when it hits an enemy would go a long way. Even just like a stock whip sound would've been good enough I think. Same for Marisa, though she at least had an sfx when the bullet was fired, but having a hit sound would've been good.
On the subject of sound, I personally liked the lack of music and ambient rain, though I understand that that's not everyone's thing. But it's nonetheless hard to ignore that there's only one song that doesn't even play for very long.
I love that the level design loops back around on itself more than a few times. The convenience that it often unlocked was fun to discover. I also love the verticality of the level design towards the end. Going over the hedge maze felt really good! Nice look back at what I had just done, while making me feel like I'm on top of the world by getting to just jump over it all after spending so long in it. Very nicely done moment.
Overall great work, I loved it~