Threats in Cooperative Games Should Compound

At the heart of any cooperative tabletop game is its challenge system. In the absence of a human opponent, players expect the game to offer a challenge appropriate to their skill level. Challenge systems often include threats that players must manage while pursuing their victory condition: fail to address a threat, and it escalates into a greater one. When designing threats, you can create better texture and foreshadowing by having them compound, growing exponentially rather than linearly.

Consider the invader deck in Spirit Island. Each invader card escalates after three rounds. In the first round, they add explorers; in the second, they build towns; and in the third, they blight the land. If left unmanaged beyond that and the invaders return to that land, they build cities and cause blight cascades. Each round the invaders are not dealt with, the consequences become dramatically worse and harder to undo. Towns and cities are much tougher than explorers, and blight exposes the entire island to additional threats through blighted island penalties and worse event outcomes.

Because threats escalate exponentially, addressing them early is more efficient than allowing them to grow. This creates interesting dilemmas: is it better to head off several emerging threats early or ignore them to clean up a disaster area that has been growing for a while? If threats scaled linearly, for example by adding one identical invader each time regardless of what is already there, then which threat you choose would matter less and gameplay would flatten to trivial calculations of what kills the most enemies.

Exponentially escalating threats provide built-in foreshadowing compared to linear ones because they start so weak that it doesn't matter if you don't see them coming. When threats scale linearly, each added threat must be significant enough to matter on its own, or else they would never add up to a serious challenge. This means you need another source of foreshadowing. With exponential threats, the trivial stage automatically foreshadows the other stages. In Spirit Island, it is fine that explorers appear at random because they are almost harmless. Placing towns or cities without warning would be a different story.

Design your threats to compound exponentially if left unaddressed. It paradoxically makes them feel fairer due to the foreshadowing while also creating opportunities for efficient play by heading them off while in the early, weak stages. Even if they make it to the terrifying stages, this is fine. Cooperative games are satisfying in part because of the us-versus-them camaraderie they inspire, and greater threats mean a greater sense of camaraderie.