The Castlevania series went through a number of growing pains during it's early years. While it's common for games in a series to be released one-after-another with little in the way of major changes (just look at the Mega Man series for evidence of that, with six main games, and five Game Boy titles, in the span on seven years), the Castlevania series saw four quick titles released one-after another, none of which really resembled each other. Sure, there was always a central character, clad in a leather, using their whip to fight the hordes of Dracula the style changed from action-platformer to proto-Metroidvania game along with the stripped down Castlevania Adventure and the over-stuffed, hybrid Vampire Killer. The series was, in short, all over the place in its early titles.
Adding to that was Haunted Castle which plays like a kind of mash-up of Castlevania and early arcade beat-em-ups (this makes sense as this game wasn't originally going to be a Castlevania-related title, but instead was converted into it half-way into development when the original concept wasn't working). The game featured six smash-em stages where the hero (presumably Simon Belmont) goes up against wave-after-wave of demons and monster all to get to Dracula and save the day (and his kidnapped bride, a character never to be seen again in Simon's storyline). Frankly, it hardly feels like a proper Castlevania.
Sure, Simon has his whip, and some variant of his sub-weapons, but the Simon in the game doesn't play at all like he does in his other games, nor is the pacing at all like a normal Castlevania title (especially when you compare it actual ports of classic game to arcades, like Vs. Castlevania or the PlayChoice series cabinets). Obviously, as this was a game that was shoved on the Castlevania team mid-way into production, it was never going to be a true adventure, not like the other games in the series. Despite this, Konami did give it a proper name in the series, calling it Akumajo Dracula in Japan, almost as if this were an arcade-remake of the original Castlevania (officially this game has no place in the timeline, effectively existing alongside the original game, even if they're barely related functionally).
On it's own merits, without the confusing back story, Haunted Castle is still an odd duck. It's brutally hard, more so than even your normal classic arcade game, like the game is daring you to play it, to see if you could ever make any progress (this, of course, feeds into that arcade, quarter-stealing loop where a player was expected to get three minutes of game play off a single coin, an industry standard for the time). Couple that with muddy graphics and a slow pace that didn't encourage the kind of light, twitch-based game play the series is known for, and Haunted Castle just pales in all comparisons to the other games in the main series.
It's no wonder, then, that it took many, many years for the Castlevania series to really come back to arcades again (with the creatively titled Castlevania: The Arcade) -- this is just not an easy series to effectively bring to the differing game play needs of the arcade format. Despite this, there are fans of this arcade game, enough so that a loving PlayStation 2 physical edition was put out for the game, complete with artwork and a soundtrack disc. That item is much prized among collectors, but only the hardest of hardcore truly care about the game play of Haunted Castle. This is an interesting oddity but a creative dead end for the series as a whole.