Of the five settlers who had just recently joined my growing dwarven community, this one stood out. Older than the others, Urist had a history steeped in blood, hunger, and rage. Though she looked like all the other dwarves—a tiny smiley face on a colorful rectangular field of numbers, letters, and punctuation—I checked out her backstory and deduced that she had to be some kind of werebeast. As quickly as I could, I input the commands to have a mining dwarf wall her up in a small cell. In theory, she could have stayed there forever, the infection contained, allowing my colony to thrive. Instead, I forgot about her and later directed a dwarf to dig out an area that included one of the walls of Urist’s prison. She was freed, assuming weregiraffe form on the full moon and attacking the other dwarves mercilessly. This is just how things go in Dwarf Fortress, a game of infinite possibilities, most of them bad.

Consumers of culture are accustomed to the idea that an album can be a commercial failure but succeed as art through its innovation and influence. We’re not used to finding the same dynamic in video games. Depending on your point of view, Dwarf Fortress could be a backwater of the medium or a raging current, a toy for detail-obsessed oddballs who enjoy playing God, or a flourishing source of inspiration, aspiration, and new ideas for indie developers and major video game publishers alike. If you can get past the difficult interface, it can even be pretty fun to play.

Once you experience Dwarf Fortress, you begin to notice its tropes elsewhere. Early in a match of Fortnite—still, at the moment, the most popular video game in the world—players must collect wood, stone, and brick from trees and structures. Later, they’ll use these materials to build pathways and defensive structures, or gain the high ground as the playable area of the game’s map shrinks, forcing the surviving players into a tighter space. Although the weapons and the shooting are important, the best builder is usually the winner of the battle royal. Fortnite came by its gather-then-build mechanic by way of another huge game, Minecraft. But even that was predated by Dwarf Fortress, where embarking dwarves (smiley faces) cut trees (brown zeroes) and build complex structures and machines, which also look like numbers, letters, or other ASCII characters. Dwarf Fortress is visually terrible, insanely difficult, and beautifully weird. It’s the video gaming world’s equivalent of John Coltrane’s Giant Steps or some crazy Captain Beefheart track, foundational music that alienates and scares those of us who are just looking for a beat to bop to, but whose influence you see everywhere, once you know where to look.

A budding tactician can train and patrol a military. A hunter can send out dwarves in search of dangerous underground beasts. A romantic can tend to their dwarves’ personal lives.

Dwarf Fortress has had tens of thousands of players (many of them coders and game developers themselves) since the earliest version was made available in 2006. Unlike most modern games, it is the product of a single coder, Tarn Adams, with creative input from his brother, Zach. Adams considers the free-to-play game, already remarkable for its depth and complexity, to be about 40 percent finished, although he recently agreed to work with members of his fan community to bring a paid version of the game to Steam, with modest improvements on the graphics. (The original version is gratis on his website.) Adams embodies a model of game developer as passionate, monomaniacal auteur, the opposite of the mainstream image of games as corporate, capitalist, and possibly addictive—not to mention collaborative works of entertainment, not solitary, personal works.

Like Coltrane’s jazz, the complexity and differentness of Dwarf Fortress are what make it difficult for those who aren’t already steeped in coding and gaming history to approach. While the unofficial motto of Dwarf Fortress is “Losing is fun,” a more accurate motto for the new player might be “Staring at an undifferentiated hash of ASCII characters without any idea of what is going on or how to affect it is fun—really!” Dwarf Fortress has no in-game tutorials (new players will have to go to the wiki for that), which is particularly irksome because the controls are unintuitive in the same way that building an airplane from scratch would be. Only after getting over the hurdle of figuring out what you’re looking at and how to use the menus to direct your dwarves can players begin to experience the real “fun” of having their carefully barricaded hole in the ground infiltrated by a weregiraffe and all their dwarves murdered or turned into weregiraffes themselves.

There is a genre of games that are difficult for the sake of being difficult, but Dwarf Fortress isn’t one of those—it’s impenetrable, but sincerely so. Played in a procedurally generated world with rules governing everything from weather patterns to dwarven temperament, it’s more simulation than game, and as simulations go it is deeply textured and incredibly complex. For example, there are 21 possible soil layers, 25 stone layers, and a further 50 types of stone that can be found in pockets and veins. There are 72 types of trees, many of which bear fruit. These trees grow based on biomes, which include tropical moist broadleaf forests and temperate coniferous forests and four more kinds of forest as well as deserts and mountains and salt marshes and more. Elements of the game often interact with one another—for instance, each dwarf has preferences, so a banana-loving dwarf will be overjoyed if the food all has bananas in it, but a rain-hating dwarf may sulk if he gets sent outside, which could lead to work stoppages or even violence.

For those who stick with it, this richness allows players to make of the game whatever they want. A builder can barricade their dwarves underground and build fantastic structures. A budding tactician can train and patrol a military. A hunter can send out dwarves in search of dangerous underground beasts. A romantic can tend to their dwarves’ personal lives. This is what draws in the tinkerers and developers and, well, cranks who play the game for free and sustain the Adams brothers with their donations and their continuing interest in every successive release. Tweaks are big and small, but always with the aim of simulating a rich world where a player can create and take part in new stories and adventures every time. One long-anticipated change, for example, will be the creation of a system for magic, an essential element to any fantasy world.

Although there have been attempts to create a more-accessible successor to Dwarf Fortress with games like RimWorld, you’re more likely to notice its influence in bits and drips. Minecraft (created by Markus Persson, who has credited Dwarf Fortress as a major influence) ushered in a craze for having building elements in games. These children and grandchildren of Minecraft often contain echoes of the specific building mechanics of Dwarf Fortress. Because of Minecraft, there is Terraria (a 2D Minecraft-like game), where building becomes a core component of strategy as the player makes arenas in which to tackle successive boss fights. In Block Fortress, another Minecraft-influenced game, building is in service to a tower-defense game. Larger gaming studios have been influenced as well. In addition to Epic Games’ Fortnite, Bethesda’s Fallout 4 incorporates building with materials scavenged from post-apocalyptic Massachusetts, which can be used by the player to build houses, settlements, and bases. (Bethesda also came out with the mobile title Fallout Shelter, which offers a colony management experience that is more directly comparable to Dwarf Fortress, although it’s orders of magnitude simpler and easier to play).

There are also direct references to Dwarf Fortress hidden in better-known games like World of Warcraft (which included a quest called “Dwarf Fortress” and two dwarven characters who made references to the game), Starcraft II, Runescape, and many more. And there are other more-elusive influences too. Beyond the building trend, there’s emergent gameplay, the term for unexpected or novel complexity that springs out of the interaction between simpler game elements. Dwarf Fortress is at once reaching for more emergence and embodying it at its best—the less-popular “Adventurer Mode” of the game is intended to take the simulated world and make it a background for emergent storytelling with a single protagonist, although for the moment that mode remains flatter and less satisfying for most players than the “Fortress Mode,” in which the player tinkers directly with the simulation itself. This desire for emergence has been at the heart of game designers’ search for ways to make nonplayer characters in story-based video games seem less flat, repetitive, and two-dimensional—in other words, more alive. This is an ongoing quest, but the independence and individuality of dwarves who form friendships, have likes and dislikes, are impacted by trauma, and even have something like proclivities and personalities has been as successful as anything that’s currently in more polished, mainstream franchises like The Sims.

It takes far more effort to learn an obscure but brilliant game like Dwarf Fortress than it does to pick up more polished, mainstream fare. But I think there’s an upside to being slowed down and forced to think, and to struggle to understand what’s going on. Instead of being carried away to a preset destination, Dwarf Fortress makes you think hard about where you want to go and question why you’ve been so willing to let other games make those decisions for you. Without Dwarf Fortress, some of the biggest games of the past decade might not exist at all, but just as important is the game and its developer’s stubborn insistence that there is more to making and playing games than the desire to addict people and take as much of their money as possible. In an environment where microtransactions make much of what passes for gaming seem more like compulsive gambling, and where visually stunning games can be shallow, repetitive and dull, that’s a huge accomplishment. Not as huge as keeping that weregiraffe contained, though.