Just adding more content to a game can only go so far -- what makes games like Rust, DayZ and Minecraft so sustainable are the social structures that emerge in the player base. Spry Fox's Dan Cook believes you can design for player relationships, and that doing so makes games live longer and keeps userbases steady. Cook's Realm of the Mad God is a fairly brutal game, featuring permadeath -- die and you lose everything you've developed and accumulated. With no respawn button, you wouldn't expect a huge number of players in the free-to-play audience to make a long term investment in the game. Yet not only does the game hold onto its user base, but its players have built a community and culture within it. "It shouldn't really work as a high-retention free-to-play title that monetizes well, but people were really sticking around for the long-term," says Cook, who became fascinated at the hierarchies, politics and power plays that emerged in his player base. Games have traditionally been a content-driven medium, Cook says, where the fundamental philosophy generally promises that more content directly creates more player value. Free-to-play games are often built on this premise, and gated in accordance with the expectation that players will pay in order to access more content. But there's a ceiling: "There's only so much content you can add before your 'evergreen free-to-play service' turns into a few weeks' activity, for most players," Cook points out. But Realm of the Mad God's players began organically creating their own value, by implementing their own social and political systems within the game. "There were orders of magnitude more interesting systems and dynamics that came out of it than what we put into it, which is very, very different than the content model," Cook says. "Lighting in a bottle happened -- and as a designer I believe random chance isn't likely," he says. "There are re-produceable human dynamics at play, here. Maybe we could have this sort of dynamic where the players are resting on a foundation that we created." Games like EVE Online, Rust, Minecraft and DayZ have similarly struck that vein of richness, where a relatively simple base rule set provides the canvas for the true value add, which is the community. People play the game because of the systems they created within it, not the systems added and implemented by designers. It's messy and challenging for game designers, but it means players actually stay with the game. Updates and significant resources can only go so far in keeping retention up -- "but if you look like something like EVE, it also has a little bit of drop-off -- but the drop-off is far less steep," says Cook. You start to get that fat tail of retention and revenue, for a very long time, and that's almost entirely driven by the player dynamics that are keeping the game alive." It ties back into motivation theory, he believes: You built a game with high agency, players can build their own society and organization, and as such experience a strong sense of ownership over their lives n the place. And because those dynamics are impossible to master, there are immensely high levels of achievement in these systems -- you couldn't master the politics of EVE Online if you spent your whole life in it. "Because one of the big aspects that drives these things is group goals and working together, you also end up getting shared purpose, and for most free-to-play games, the idea of shared purpose as a group... is absolutely missing," suggests Cook. Millions of people participated in Twitch Plays Pokemon, where no individual was able to impact the game alone. "What ended up happening was all these groups formed outside the game to talk strategy, Reddit had forums full of propaganda posters," says Cook. "It became almost a religious phenomenon... where the individual was massively unempowered, but as a group they could accomplish stuff together." Relationships are based in reciprocation loops, Cook explains, where one person makes an overture and the other person reciprocates. Studying those loops, and where and whether they break down, is constructive. A lot of game design involves zero-sum transactions, where if one person has something, another person doesn't, for example, and designing for mutuality and reciprocity helps -- "It doesn't matter if there are lots of free riders, if everyone is benefiting." Free-to-play games generally fail at escalating -- even Candy Crush Saga contains reciprocity loops where players can give one another lives and things, but there's no way to deepen those interactions. The factors in building relationship with games are proximity ("are we near each other, is there a high likelihood we are going to bump into each other"), repeated, informal encounters ("you don't need to make plans"), similarity, and the ability to share feelings and ideas. Realm of the Mad God had a hub that acted as a social space -- it was a design decision that created the opportunity for players to start recognizing names on their local board and encounter them informally and repeatedly. People tend to make friends with people who are in some way clearly similar to them. You want groups to cross-pollinate, but one of the strongest ways to create community in the first place is to have opportunities for people to be similar to one another. Designers often fail, Cook believes, to give players the infrastructure to share ideas and feelings. Thatgamecompany's Journey has reciprocation loops, is multiplayer, and brings people together. "However, because you can only beep at one another, you can never explore those ideas and feelings. We don't see the same level of emergence in something like Journey, even though it's an extraordinarily well-designed multiplayer game, that we do in other things." League of Legends has a very rich feedback system for players that "screw up," says Cook. "In highly-competitive matches, if you're doing something wrong, everyone is immediately on your case." The game is almost famous for such unpleasantness, but in spite of that its user base grows and is steady. "When I dig into what makes rich communities, this type of drama seems to be essential," Cook says. "The storming that happens when groups come together and create social norms is essential... the individual has to give up a little something to become part of the group, but the trade-off is the group is stronger because of it." "Norms are violently-negotiated social contracts," Cook says. DayZ is popular for its emergence, but its social structures are fragile -- persistence is "pretty crappy." It's a permadeath game that lacks the sort of social persistence that Realm of the Mad God has, and feels like a bigger space where you rarely re-encounter the same people. That makes it hard for social structures to emerge, he says. Stressing the system is key for making governing structures emerge, Cook says. "Government is a social technology... that we're implementing in order to solve broken things," Cook says. "We want relationships, we enjoy them, and we enjoy working together, and we implement the techniques of governance in order to get there when the group is too big or the task is too complex. Governance emerges as solutions to problems." "You seed the relationship systems, and then you stress them, and the community reacts by adopting these social technologies," Cook says. "...Players are this massive, generative source of value, and that's what keeps our games alive long-term."