The story stack is a concept presented by Jesse Schell, author of The Art of Game Design, at GDC 2019 (his talk starts at 51:00) — and it’s one of the most valuable concepts I learned during Susan O’Connor’s Game Writing Master Class. The story stack provides a means of understanding and approaching the various elements of the game development process, sorting them from least flexible (Player Fantasy) to most flexible (Story).

With an understanding of the story stack in place, the development of the gameplay, economy, worldbuilding, and story can be developed in order to best serve the player experience.

In this analysis, I break down the story stack elements for Horizon: Zero Dawn, examining how they fit together to serve the player fantasy. In the end, I present a thought experiment exploring different story concepts while utilizing the story stack.

The Horizon: Zero Dawn Story Stack

Player Fantasy: Explore and become the savior of a post-apocalyptic scifi-fantasy world filled with giant dinosaur-like machines. 

Actions: The player explores the world through walking, riding of machines, and platforming (climbing mountains, using ropes, and zip lines). When the play encounters machine or human enemies, they implement a combination of stealth and combat mechanics (with a variety of weapons) to either avoid, trap, or defeat machine and human enemies. Another key element is the player’s ability to use technology to analyze enemies and situations, as well as manipulate mechanical systems throughout the world.

Economy: The economy of the game includes a variety of elements. Missions involve a mixture of stealth, combat, and treasure finding, which provide skill points, crafting items, and money (in the form shards), which allow the player to unlock new abilities, obtain better weapons and armor, and craft ammunition, potions, and other useful tools. In addition, missions will enable the player to gain access to new areas and communities within the world. 

World: Set in a post-apocalyptic future, the world exists among the ruins of the past. Wild animalistic machines roam various ecological biomes, including hillsides, forests, jungles, deserts, and mountains. These machines are deadly when they attack, but provide valuable resources that the various tribes utilize within their communities. This includes money, building materials (for homes, weapons, tools, clothing, etc.), or even as adornments (jewelry or decorative details on clothing). 

The tribes consist of the surviving humans, and each tribe has its own unique cultural perspective. Some of the main tribes are: 

• The Nora are a matriarchal society that worships the All-Mother, a goddess who defeated the old world demons (machines). The society believes the old world is responsible for destruction and, therefore, technology and knowledge from the old world should be shunned. 
• The Oseram are a tribe of tinkerers and craftspeople, who are technologically advanced tribe and known for their metalworking skills. They believe in innovation and are able to create powerful weapons. 
• The Carja are primarily situated in a well-populated, towering city ruled by the Sun King. The Carja worship the sun and have advanced beyond many of the other tribes in terms of their writing system, economics, and military. 
• The Banuk are a nomadic tribe with strong warriors and shamans, who value independence and personal strength over all else. They worship the Blue Light (the glow emanating from machines) and, in the past, have been able to tame and control them. 

Story: An outcast of the Nora from birth Aloy longs to become a member of her community. She decides to participate in a series of tests that would allow her to become a warrior and full member of the Nora tribe — and hopefully learn the truth as to why she had been cast out as an infant. However, during the test, the Aloy and the Nora are attacked by a violent cult able to control corrupted machines. 

Believing that the tribe is in danger, the High Matriarchs grant Aloy permission to quest outside of the village in order to uncover the source of the corruption — a quest that may also reveal answers about her past. As Aloy journeys out into the world, she seeks out information from other tribes and uses a technological device she found as a child to delve into the true history of the human race and how it was destruction in order to save the world from a new and terrifying threat. 

New Story Concepts

Since story is the most flexible element in the stack, this thought experiment considers what would happen if the game developer decided to toss out the entire story for Horizon: Zero Dawn. Assuming all the rest of the story stack remains the same, here are three new concepts for the game.

Story Concept One: In an alternative history for Aloy, she is a young woman who has trained her entire life in the sacred ways of the Nora, with the expectation of becoming a High Matriarch. After a series of tests, she is selected for initiation and welcomed into the sacred temple, deep in the earth, where she comes face to face with the altar of All-Mother. During her initiation ceremony, in which she must kneel alone overnight in the temple, the All-Mother opens, revealing itself to be a doorway that leads deeper into the earth. She follows the passageway down into the depths and uncovers a secret of a deadly danger — forcing her to choose between her current path or risk becoming an outcast in order to save her people. 

Story Concept Two: When a young Banuk warrior and his fellow hunters are attacked by corrupted machines, the warrior begins to question his faith in the Blue Light and the teachings of the shamans. He doubts the truth of the shamans stories, which speak of cooperation between humans, machines, and nature. Nevertheless, he joins a group of warriors that have been tasked with seeking out what has caused the machines to become corrupted — but as they set out on their journey, they are once again viciously attacked. As the only survivor, he vows to find the truth or die trying. 

Story Concept Three: A Carja soldier is assigned to protect the Sun King and his family. When a seemingly impossible assassination attempt is made on the king, she begins to investigate who the killers are and what technologies could have enabled them to gain access to the palace. The investigation carried her far out into the world, evading machines and bandits. As she uncovers the truth, she discovers a deeper mystery that puts not only her home of Carja at risk, but the world.