Board games don’t traditionally foster teamwork . From the cutthroat capitalism of Monopoly to the one-upmanship of Catan’s “longest road,” the tabletop is a battleground where friends become rivals and parents bankrupt their children. This has always felt a little off to me. We’re a social species… why do our games always pit us against each other?

It may be that we simply need something to challenge us, something as dynamic and unpredictable as a human being. Until recently, tabletop games had nothing like an AI opponent, and so you were forced to choose between a dull puzzle like Solitaire or a combative, winner-take-all game like Risk.

In the 1980s, a few cooperative games started to change this formula. In Scotland Yard, a hack was introduced that finally allowed players to work as a team: one person would play as the elusive “Mr. X”, an enemy with his own agenda and rules,while everyone else ganged up to destroy him.

It’s Mr. X (foreground) vs. every detective in London in Scotland Yard (1983)

The idea had promise, and led to other great “all against one” games of this era such as Fury of Dracula and Arkham Horror. These are all great fun, particularly if you have a friend who enjoys playing the asshole. But they still divide players; they aren’t fully cooperative.

This all changed in 2010 when Matt Leacock introduced a “virus” mechanic in his game Pandemic. The virus is your collective opponent: like an AI algorithm from a video game, it’s just a set of rules, but it’s simple enough that your teammates can run the program themselves.

Two infections, represented by black & red cubes. Red is about to go viral in Hong Kong.

At the end of their turn, each player follows the rules of viral growth. They simply draw a card and place virus cubes on the city shown. If there are already too many cubes there, an outbreak is triggered, infecting adjacent cities. This can then trigger further outbreaks, going from bad to worse in very little time if players don’t carefully combat it.

This little indie game became a big sleeper hit, and ushered in a slew of innovative games with a viral threat. From the rising floodwaters in Forbidden Island (2010) to a house consumed by fire in Flash Point (2011), players found this sort of relentless, emergent foe to be as challenging as any human opponent. Perhaps most notable, they found that without strong coordination and consensus-building skills, your group didn’t stand a chance.