The media revolution precipitated by the Internet developed in more or less expected fashion. We can watch movies at home while they’re still in theaters, websites are independently developing award-winning TV shows, and the book industry has been gutted and left for dead. There’s something missing from the spectrum, though: the webseries. Six or seven years ago, the explosive popularity of lonelygirl15 and the cast/crew brand legitimacy of Dr. Horrible’s Sing-Along Blog implied the birth of a new medium for visual storytelling. It seemed like a natural progression, from the cinema to the television to the Internet, but it didn’t end up coming to pass. The idea evolved into the high-profile online television offered by Netflix and Amazon, and the original definition of “webseries” lost almost all its relevance. It’s a medium ripe for exploration and inventiveness, but you’ve likely never heard of the ones that succeeded.

In other words, you’ve probably never heard of Marble Hornets, a YouTube webseries that ended a five-year run back in June. It’s one of the best uses of the format in existence, challenging expectations not just of what a webseries can be, but of what long-form storytelling should be. It’s important to say this up front, because describing the series in broad strokes is going to turn some people off. The series revolves around an investigation by protagonist Jay (played by co-creator Troy Wagner) into mysterious tapes left to him by his friend Alex (played by Joseph DeLage, also a co-creator). During the production of Alex’s student film Marble Hornets, he began behaving strangely and later broke off contact with everyone he knew. Jay initially wants to finish shooting the film, so he gets the tapes from Alex and finds that they contain multiple appearances of a mysterious faceless man.

There are three things you might have picked up on in that synopsis, and they’re deal-breakers for some people: It’s found footage, it involves Slender Man, and it offers more questions than answers. You shouldn’t let those things discourage you. I agree that found footage is rarely used effectively, I’m generally annoyed by the Slender Man meme as well, and while I don’t share frustrations regarding unresolved endings, I can empathize with them. The good news is that Marble Hornets does all of these things right.

Let’s start with Slender Man, because people will undoubtedly make some incorrect assumptions about the series based on this fact alone. First of all, Marble Hornets isn’t yet another crass attempt to cash in on the popularity of the meme. In fact, the series started only ten days after the character was created on the Something Awful forums. Marble Hornets could actually be credited with introducing most of the Internet to Slender Man, although it really broke out a few years later and Marble Hornet’s incarnation of it shares few of its traditional characteristics.

This series calls it “The Operator,” and it appears in less than a third of the series’ 87 episodes. The Operator can’t be considered an antagonist, as its motivations are left entirely unexplained. Marble Hornets understands monster dynamics better than most monster movies. The Operator’s appearances are always terrifying, but only because they are rare and confusing. It appears at seemingly random points in the narrative, so even more mundane episodes are imbued with its presence because it could show up. We’re never given a clear picture of what it can do, so its abilities could be limitless. The key factor is its lack of discernible motivation, which feeds into a Lovecraftian fear of things we can’t comprehend. There are plenty of scary monster designs, but The Operator has no design at all. It’s a screen on which we can project individual anxieties, making it one of the few monsters that can scare pretty much anyone. The absence of information is a theme of the entire series, and you’re often left unsure if you even want it to answer its questions. Possibility will always be more engaging than explanation.

Marble Hornets stands out as horror fiction, but it excels because it takes full advantage of its medium. I’ve expressed my feelings on the misuse of found footage in the past, and Marble Hornets is probably the best example of the aesthetic. It is fully committed to the form in a way that found footage cinema can’t possibly be. Every part of the series is designed not to resemble fiction, beyond the footage itself. Like The Blair Witch Project, it claims to exist within our reality, but as a webseries it can play more with this idea. The episodes were uploaded to YouTube by the main character, and they had title cards that spoke directly to the viewer. None of the videos allowed comments, so the audience couldn’t intrude on the verisimilitude of the series. Episode runtimes varied wildly, because a real person wouldn’t be concerned with keeping each episode to a particular length. Episode releases were also sporadic, always appearing on the channel at random times and without fanfare. The last few episodes were released weeks, sometimes months apart, and the series finale was so vague and inconclusive that the creators had to come out and announce that there would be no more episodes.

The mad genius of Marble Hornets is in its refusal to put entertainment first. Many an episode was made up of lengthy sequences of people walking through a forest, or an abandoned building, or similarly desolate spaces. A found footage movie can justify cutting around the boring parts because they can only be so long. The “raw footage” from Paranormal Activity would be mostly made up of two people sleeping, undisturbed by so much as a mysterious gust of ghostly wind. Marble Hornets doesn’t cheat. It knows that its main characters can’t possibly experience something strange and exciting every time they turn on the camera. Marble Hornets is horror with thematic intent. This is a show about investigation and process. It’s like a supernatural Zodiac.

There was also something of an ARG element to the series, starting with the “totheark” videos. After only a handful of episodes, an unidentified channel with the username “totheark” stared posting video replies to each episode. This channel was the total antithesis of Marble Hornets. As opposed to the strict realism of the main series, “totheark” was clearly influenced by experimental film. The pace of the editing is uneven, the images are abstract, and the messages are meant specifically for Jay. “totheark” videos were distorted, manipulated, and deconstructed, while Marble Hornets always presented unaltered footage (in the universe of the show, at least). They all included hidden messages and codes, some of which still haven’t been cracked. On the whole, these videos are much, much scarier than Marble Hornets. While collecting videos for this article, I couldn’t handle watching these again. It was unsettling enough to see footage from the series repurposed by “totheark,” but after a while the videos started including footage of Marble Hornets characters that “totheark” captured themselves, always when the characters were unaware. On a couple occasions, “totheark” uploads videos to the Marble Hornets channel. And like The Operator, “totheark”’s identity can only be guessed at and their motivations are even more opaque.

While most of the series focused on process instead of thrills, Marble Hornets features some seriously stunning filmmaking when the story ramps up. The bane of found footage is the insistence on a “motivated” camera, which means that there always has to be a reason for the camera to be filming and seeing scary stuff. The series skirts this issue in a couple ways — most often through the character who straps a camera to his chest all the time — but by far the best is when it has the camera sees things that the characters don’t. The premise is built on this idea, as the dailies from Alex’s film shoot show The Operator lurking in the background even though no one on camera notices it. In my favorite episode, “Entry #72,” Jay and Tim (Tim Sutton) search for clues in Alex’s old house. Early on, Jay panics because he thinks he sees The Operator outside. Tim doesn’t see anything. There’s a cut as Jay shows Tim the footage, thinking he captured it on camera, and when it comes back we hear Tim say something about taking Jay to a doctor. A couple minutes pass without any hint of a disturbance. At one point, Jay sets the camera down to help Tim force open a door. The camera is pointed out a window, and we see The Operator standing motionless and staring at the house. The sky darkens, and Jay picks up the camera, neither of them having noticed. This is a fantastic use of the format, because it introduces the tension of when the characters will see the scary thing separate from when the camera will see it. A common mistake with found footage is in gluing the camera to the protagonist’s eyes. If the camera never acts as a distinct element, then its presence hasn’t been properly justified.

There are moments of bravura filmmaking outside of the use of found footage as well. In “Entry #23,” Jay chases a masked man (who is implied to be “totheark” at the time of this entry) through a house and starts teleporting when he walks through doors. It’s a seamless effect, and it succeeds because they don’t draw any attention to it. Jay doesn’t talk to himself about what’s happening, there’s no sound effect for the teleportation, it’s just something that happens. The benefit of being a low-budget webseries is that you’re forced to resort to simpler tricks in place of modern special effects, like the editing magic in this episode (as well as in “Entry #65” and “Entry #83”) or the audio/video distortion that always accompanies The Operator. This isn’t a flashy series, but a stronger emphasis on these elements could only make them less effective.

The series had plenty of imitators, but none of them were as intelligent, impressive, or frightening. I’ve been scared by movies and TV shows before, but Marble Hornets is one of the only things that’s ever made me afraid of the real world. I can’t remember how many times I’ve looked over my shoulder while watching an episode because I can feel something watching me, or how many times I’ve paused an episode to turn on some more lights. Marble Hornets is, if nothing else, a series about paranoia. The Operator rarely shows up, but the fear of it drives the main characters to darker and darker places, and they force viewers to go along with them. Through its depiction of anxiety and paranoia, it makes the audience anxious and paranoid. Every aspect of its production contributed to this, right down to the seemingly random episode releases. Marble Hornets begins with a box full of mysteries and spends its entire run making you afraid of opening it. The comparison to Lovecraft is quite apt, because the series never makes its unfathomable terrors understandable to humans. And what is paranoia but a fear of the unknown?

Marble Hornets was the apotheosis of the webseries as a medium. It started in mid-2009, just a year or two after the webseries boom, and it ended exactly five years later, long after the webseries effectively went extinct. Today, it’s mainly used by corporations as “viral marketing,” or by production companies who have a more significant budget. Shows in the vein of Marble Hornets just don’t exist anymore on its scale. Its great tragedy is that it proved the medium’s potential too late to save the concept from irrelevance. It’s hard to even categorize it now. Hopefully, that won’t lead to it being forgotten when historians list the important bits of pop culture from the Internet era. This is a series that deserves to be influential. At the very least, it deserves to be watched.