The NES Castlevania remains a high point in my entirely too lengthy history of gaming, and I know many others feel that way. With luck, this series has provided some small amount of clarity on the qualities that have made this trio of titles so enduring.

On a macro scale, the NES Castlevania titles feature some of the most consistent mechanics and visuals ever shared within a series, yet the objectives and structures built around these fundamentals vary wildly from title to title. Sure, 8-bit Mega Man and Sonic on Genesis retained consistent rules and design from title to title, but neither of them took a radical side excursion into non-linear world design along the way.

As I’ve pointed out with what no doubt must be irritating frequency, the Castlevania games at their best were defined by the attention to detail and consistency the team invested in their worlds. From the accurate level layouts depicted on the castle map overviews to the alignment of background structures from screen to screen, the creators of Castlevania set their work apart by investing it with careful consideration previously unseen in action games, which until then tended to depict their worlds through abstract, repetitive tiles, if at all. The Castlevania teams took great pains to create visual continuity and detail that most people never consciously noticed without compromising the game’s playability—all the more impressive considering the limited palette of visuals available in the memory space of a Famicom Disk System title.

Still, as countless beautiful yet terrible games through the years have proven, no amount of obsessive detail and design discipline can make a poorly designed game fun. Thankfully, the people behind these games were as scrupulous about the nuts-and-bolts of the action as they were the superficies of the backgrounds. From the very beginning, the Castlevania play style operated on a very reliable, intensely consistent set of rules. Simon (and later Trevor) moved at a fixed pace, could jump a set height and distance, and wielded weapons with clearly defined power, range, and purposes. The sequels built on this, granting Simon greater strength and more non-combat tools in Simon’s Quest and gracing Trevor with a squad of companion characters whose play mechanics diverged considerably from his own in Dracula’s Curse—but always logically, and always reliably.

Of the three games, the original Castlevania represents the purest expression of these components. With six levels, it’s the briefest of the games—just long enough to fully explore Simon’s tool set and establish a difficulty curve that goes from “gentle” to “insane” with only one or two wakward bumps along the way. Castlevania laid down the groundwork for the franchise: Not just its NES sequels, but subsequent games on Game Boy, PC Engine, Genesis, and in the arcade.

Castlevania remains the most collected and remade title of the entire franchise. Some of that is due to timing: The game launched right as the Famicom tightened its grip on Japan and the NES began exploding onto the scene in the U.S. It’s fondly remembered by an entire generation of adults who as children obsessed over their new game console, and even if it lacked the depth and technical prowess of its sequels, it stood out amidst so many more aimless and unpolished adventures in the early days of the NES. It established a high-water mark for gaming at the time, and as such became something of a legend… deservedly so. Even beyond direct recreations like Super Castlevania IV and Castlevania Chronicles, you can see its fingerprints all over subsequent games, be it in the enemies, the tools, or the loving recreations of the first stage’s castle entrance.

Simon’s Quest took the core mechanics of jumping, whipping, and moving with deliberate precision and spun them in a different direction. Rather than sending players though six linear stages, Simon’s Quest focused on six buildings (five mansions and Castlevania itself) spread across the Transylvanian countryside. The mansions lacked the intense challenge of its predecessor’s stages; instead, much of the difficulty stemmed from navigating both the countryside and the NPCs’ unreliable “tips.” Much of the design discipline that defined the first game proved to be in absence here, with stage and world design unfolding as more of an aimless sprawl.

You can guess the reason for this divergence from the two other games released between Castlevania and Simon’s Quest: Vampire Killer and Haunted Castle. The former, a linear but exploration-heavy action game for the MSX computer, probably seemed a better direction to define the console game than the latter, an unevenly designed coin-op game that cuttingly demonstrated the limitations of the arcade format. I don’t doubt the Simon’s Quest team saw a rambling RPG-inspired style as a better means by which to foster longevity than the simple stage-by-stage structure. But, as with so many attempts to reinvent the wheel, they didn’t think it through as thoroughly as they ought, and the result was a well-intentioned mess.

Dracula’s Curse brought a near-perfect balance to the series. The designers returned to the original Castlevania’s format, yet they didn’t completely abandon the concept of exploration and discovery. Instead they encouraged replayability by creating multiple routes through the game and a trio of alternate characters (only one of whom could accompany the hero at a time); despite technically being a linear adventure, Dracula’s Curse consists of 17 stages total, and a player would have to play through the game roughly a dozen times to experience each level in every possible permutation.

This was made possible by the increased cart capacity available by 1989, offering far more space for content than the limited FDS had. Even so, you can see Dracula’s Curse straining within its limitations. The lower map route in particular seems to run out of steam midway, recycling graphics and hazards, and occasionally leaning on questionable level mechanics that feel unworthy of the rest of the adventure. It consists of about a dozen excellent stages and five mediocre ones—though, in fairness, that’s still twice as much content as the entirety of Castlevania, and a far more satisfying experience than any portion of Simon’s Quest offered.

The Castlevania trilogy boasts a remarkable amount of evolution and experimentation—rare enough traits on their own, but in service of genuinely excellent action games? That’s absolutely remarkable and completely cements the series’ place in gaming history. I’m wary of the franchise’s current direction, but the good news for Mercurysteam is that some kind person on the Internet has taken the time to break down what made Castlevania great to begin with. It’s all right here, guys. I can think of worse approaches to game design than looking back to the formative nuts and bolts of the property you’ve been handed.