Horizon Zero Dawn by Guerilla Games is a game that's first and foremost about the story. It's woven into every area, level and cutscene. Its main goal is to take the player on Aloy's journey to discover the secrets of her past and halt the mechanized threat poised to bring this new world down around her.
Like Horizon Zero Dawn, the Fallout series follows a protagonist through its own post-apocalyptic wasteland. However, unlike the world in Horizon Zero Dawn, there is no resurgence of life. No hope for a better future. In Fallout, people simply live in the ruins of the old world and try to do their best to get by. Despite their contrasting takes on the post-apocalypse, both share a similar style of environmental storytelling.
The Fallout Style of Storytelling
Both games have a physical link to the post-war history of their worlds. With Horizon Zero Dawn, it's the Ancient Ruins, while Fallout uses a plethora of old Vault-Tec Vaults spread across the wasteland. Both can be found as locations in the world, and both hold secrets of the setting's past and can be explored by the player. With Horizon Zero Dawn, however, these caches of historical knowledge are few and far between and are slightly more restrictive in what can be found in them.
Vaults in Fallout, on the other hand, tend to have their own environments and stories associated with individual vaults with their own item placements and themes. For example, in Fallout: New Vegas, there is Vault 22, which has seen itself go from a safe haven for survivors to a botanical nightmare thanks to scientific experimentation. While in Fallout 3, there is Vault 87, which, through its forced evolutionary experiments, caused the Super Mutant crisis in the Capital Wasteland. The same variations just aren't there for the Ancient Ruins in Horizon Zero Dawn, which largely consist of dilapidated buildings.
Hints Are on The Horizon
Much like Fallout, Horizon Zero Dawn tells its broader story through objects in the environment. While playing the game, Aloy can come across audio logs, text logs and scenery telling the story of events that took place in the old world. There's no need for another NPC to tell her this information directly. It's all ambient. The same can be found in Fallout's world, such as Fallout: New Vegas' Vault 11, where the player can follow notes and audio logs left behind by previous residents to learn about Vault-Tec's horrifying experiments.
Both games refuse to tell the player small story beats directly. Instead, they leave behind a bread crumb trail of clues that allow the player to piece the information together and work out the answers for themselves. Not only does this method convey the story it wants to tell in a clear way, but it also makes the players more invested in the game world as they dig around in their environment for more clues and story hints that they may have missed.
Investigating the environment is a key feature of both games, though Horizon Zero Dawn does this in a style more similar to The Witcher III, while the Fallout games don't have an active investigation mechanic. Fallout relies on the player themselves being aware of the clues they find. This makes story clues in Fallout harder to spot and more of a challenge to find, but also makes that challenge a lot more rewarding.
Both games share a 'scavenger hunt' approach to storytelling, but Fallout seems to use this method for a wider variety of quests, while Horizon Zero Dawn uses it to streamline the weirder narrative of Aloy's world. Through various notes and interactions, Aloy can find background information on the old ones, as well as context and further insight into the more personal story that's taking place over the course of her journey. It's ultimately it's up to the individual player to decide which variation of the method they prefer the most, but Horizon's mastery of ambient storytelling wouldn't exist without Fallout setting the standard.