Reports claim that Horizon Zero Dawn doesn't just have a sequel in development, but plans for a whole trilogy. VGC reports that multiple sources have told it that Sony Interactive Entertainment has greenlit the series.
Apparently, Guerrilla Games had always planned for Horizon Zero Dawn to become a trilogy if the first game did well. And this seems pretty apparent considering how the original title ended.
Since Horizon Zero Dawn did spectacularly, Guerrilla Games went to work on a sequel not long after the original's release. The developer was initially going to launch the title on the PS4. But since next-gen consoles are on the way, the sequel will instead release on the PS5.
And supposedly, this sequel will be "gigantic" in scope. VGC claims that it'll feature a much larger world than the original, one that will allow players much more freedom in exploring. This statement makes it sound like the game will feature more transversal mechanics, as Horizon Zero Dawn didn't really limit where the player could go.
Evidently, the sequel will also have a multiplayer feature, which is something that a recent job listing seems to lend credence to. Guerrilla had plans to develop a multiplayer function for the original Horizon Zero Dawn, too, but scrapped the idea in favor of developing other parts of the game. How exactly the multiplayer will work for the sequel remains a mystery, however, as nothing specified whether it would be apart of the story mode, something else, or both.
Although, Guerrilla reportedly use to have plans for a standalone Horizon Zero Dawn multiplayer project. It would have acted as a preview to what players could expect in the full sequel. This project would also allow players to carry any progress that they made over into the full sequel when it released. However, judging by the way VGC words Guerrilla's description of the project, the developer no longer has plans to put out such a title.
But beyond these rumors, evidence for Horizon sequels does exist. Back in 2017, Former Sony Interactive Entertainment America President Shawn Layden told The Telegraph that PlayStation planned to continue Horizon Zero Dawn in the future. He also said that Guerrilla Game's co-founder, Herman Hulst, had a roadmap for Horizon that stretched across years.
Herman Hulst is now the new president of Sony Interactive Entertainment Worldwide Studios, so it seems pretty safe to say that he would be onboard with greenlighting anything Horizon related. And if all of that weren't enough, the game has a canon comic book continuation releasing in July 2020.
Horizon Zero Dawn released on February 28, 2017, for the PS4.
Source: VGC