Dark Souls may get the glory for influencing a decade’s worth of games, evident by the number of times “The Dark Souls of [X]” has been used as shorthand to describe video games this decade, but Demon’s Souls blazed the trail.

Demon’s Souls is the oft-neglected pioneer that led to many modern games, overshadowed by its more fully realized and more polished successor, Dark Souls. But in 2009, few game developers were taking risks the way FromSoftware had, ultimately reshaping the company and altering the future of game design.

The precursor to Dark Souls even confused its original publisher, Sony, which had difficulty pitching it to PlayStation 3 owners. Early on, it opted not to release the game outside of Japan. Publishers Atlus and Bandai Namco picked up where Sony left off internationally, and executives at PlayStation now look back on the decision to not release Demon’s Souls outside of Japan as a mistake.

(I should note that Demon’s Souls first arrived in early 2009, making its release technically prior to this decade. But given its protracted publishing schedule, players in Europe didn’t get the game until 2010, and Demon’s Souls’ influence will assuredly spread not just into this decade but the next as well.)

Ultimately, Demon’s Souls went on to influence dozens of games, and even the very design of the PlayStation 4 itself, according to the former president of PlayStation’s Worldwide Studios, Shuhei Yoshida. The game’s asynchronous messaging system and the ability to learn from other players’ mistakes helped inspire the Share button on the PS4 controller, Yoshida said.

Demon’s Souls’ combat control scheme, using a gamepad’s shoulder buttons for attacks, which carried on through Dark Souls and Bloodborne, has been lifted wholesale by other franchises, some which already had established combat controls, over this decade. The recently released Star Wars Jedi: Fallen Order — a Star Wars game! — borrows the soul-retrieval and enemy respawning mechanics popularized by Demon’s Souls (and later refined with Dark Souls’ bonfire system). Demon’s Souls’ message system, in which players can leave pieced-together sentences as warnings or words of support, is present in Death Stranding, in which players can leave each other signage to let them know they’re not alone in their own bleak world.

Demon’s Souls has since spawned dozens of imitators and homages: Nioh, Lords of the Fallen, The Surge, Titan Souls. Games like these give players a sense of hopelessness and being overwhelmed by the spaces they inhabit. They present Demon’s Souls-like levels of challenge, encouraging players to persevere, to become stronger and more skilled in order to face daunting tasks.

What made Demon’s Souls so special was its opaque and difficult nature, design choices that were antithetical to conventional game design wisdom at the time. While Demon’s Souls contemporaries — sequels to Uncharted, Mass Effect, and Assassin’s Creed — went for big, Hollywood-style adventure stories that were player friendly, developer FromSoftware bucked tradition with a role-playing game that was both retro and visionary.

Much has been made of the Souls series’ difficulty, but its challenges were oftentimes misunderstood as simply masochistic. A giant dragon would kill players early on with a single hit. After all, you are but a human, dwarfed by an ancient monster. How would you possibly stand a chance? And Shrine of Storms, a windswept, rocky island, was full of peril because it was easy to simply walk off a ledge and plummet to your death. But it was merely a world without guard rails where you, the player, had to exhibit a similar measure of caution as you would in real life. The poisoned swamps of the Valley of Defilement made for a frustrating journey of constant sickness and diminishing health, because why wouldn’t a world of decay and pestilence be anything other than a horrid place to exist? Demon’s Souls could be miserable, for it was set in a miserable world.

Much has been made of the Souls series’ difficulty, but its challenges were oftentimes misunderstood as simply masochistic.

Demon’s Souls’ ambiguous rules, complicated by its unusual World and Character Tendency systems, reflect what we often crave from our best entertainment: complexity, depth, and reward for investing our time and attention. But even the Tendency rules of Demon’s Souls ultimately proved too unwieldy for FromSoftware to continue forward with (Dark Souls would later explore similar themes with its Covenants system, which lacked the personal and world-altering effects of Demon’s Souls’ shifting light and dark structure).

Demon’s Souls’ multiplayer rules would find their way into future FromSoftware games; players could summon others to aid them in battle — or could be invaded by other players who wanted to inflict cruelty on them, even though we’re all just trying to get by in this struggle for existence. Soon, other games would adopt similar features, letting players visit and speak to each other — and kill each other — in previously unconventional ways.

Demon’s Souls’ upending of expectations of what video games should and could be at the start of this decade has been felt throughout the last 10 years. And looking at some of 2019’s biggest new releases, it will continue to inspire game creators for years to come.

The most influential video games aren’t always the most popular, and rankings never tell the whole story. To mark the end of the decade, our editorial team published a list of the top 100 games . We’ve also created this supplemental series, in which individual Polygon writers get to talk about the most important games from that same period, and exactly how they changed the course of the industry.