I like it so far
YESS!! The Rondo Stair jump!! You are doing awesome so far!! This is will be the best CV3 hack!!
Thank you! I'm really glad to hear that people are interested in this.
Which "most games" are you talking about ? "Most games" does not have the awful stairs system Castlevania has, including even later Castlevania games. You mention Super Smash Bros but it's completely different from Castlevania so it makes no sense comparing them.
My philosophy here is that I should disregard the way that CV3 was intended to be played in favour of making the controls (and the way the player interacts with the world) standard and intuitive. As such, CV3 should have the same control scheme that any sensible modern platformer game would have. Smash Bros. is, in my opinion, the greatest platforming engine ever devised; movement in Smash Bros. is absolutely flawless and is completely intuitive. Even though the in-game objectives of Smash Bros. and CV3 are quite different, they are both -- at the fundamental engine level -- platformers in my mind, and therefore warrant similar control schemes.
In Smash Bros., there are not "stairs" as such, but there are slanted ramps that one can jump and fall through. In my mind, this is actually exactly the same as a stair and I see no reason to treat stairs and ramps differently at all. They are both slanted platforms the player can stand on, walk along in either direction, and fall through.
Therefore, stairs in CV3 should function in precisely the same way that ramps do in Smash Bros.
My only point of comparaison is later Castlevania games who DO have stairs, those are Super Castlevania IV, Rondo of Blood and Castlevania Bloodlines. You'd want to behave
like those whenever possible.
Of these, I've only played SCV4, which as I recall had an annoying control scheme as well. I wouldn't personally want to model the controls off of that game. I suspect that most people who haven't played any Classicvanias would prefer a Smash Bros.-style control scheme, and some
people who have gotten used to the SCV4-style control scheme would prefer that to a Smash Bros. style.
The original CV3 has consistent and predictable behaviour, yet we both agree it's controls suck.
How does it make the controls inconsistent ? SCV4 probably does exactly that. If the stairs go "down", you autoland on them, as this avoids falling through stairs like shown in this video. If they go "up", you don't autoland and simply pass through. This is absolutely consistent and makes sense. If you jump in front of stairs going up, you just do it as if the stairs weren't here. If you jump over stairs going up and fall in a bottomless pit, and die which is the correct behaviour. If you jump hop onto stairs going down, you land on them, as opposed to the original game, again the correct behaviour.
I suggest checking the vertical position as a simple way to distinguish stairs going "up" from stairs going "down" but if there is another preferred method, go for it.
Firstly, "up" and "down" are not properties of the stair, but of the player -- any stair could be either an "up" or "down" stair depending on perspective. The only difference in stairs is whether they are parallel to y=x
Secondly, even assuming your other premises, sometimes "up" stairs ought to be solid/auto-catching, such as the stairs just before Dracula. So "up"/"down" is not a good qualifier for whether a stair should be auto-catching.
Thirdly -- the reason I would consider that proposed behaviour "inconsistent" is that it depends not only on the current state
of the character (x,y coords, velocity, health points, subweapon) but also on the path
the character has taken to get there (i.e. whether the player used to be higher or lower). Look up "State function vs Path function" for a more rigid definition of these terms.
I believe controls should always be sensitive to the state of the player, but not the path. I would call path-sensitive controls "inconsistent" because the player would not always predict how their controls will influence the game based solely on the information presented to them on-screen.
Players generally assume that controls are state-sensitive and not path-sensitive; as a result, I believe they would find controls to be less learnable if they actually did depend on state as you suggested. Instead, the player would be confused why sometimes they fall through stairs by default and sometimes they land on them by default.
And that would be horrible.