Horizon Online could be a big project. According to one developer it has been in development for over 5 years – INDIAN

In a Dutch studio Guerrilla games after Zero dawn horizon And Forbidden Horizon West they are preparing Aloy’s third story adventure, and are also developing multiplayer project set in this interesting world (confirmation here). They called him Horizon Online and apparently it will not be a canape, but a full-fledged name.

This is stated in the profile of one developer on LinkedIn. He states that he has been working as an online game director at Guerrilla Games on Horizon Online since February 2018, i.e. 5 years and 7 months. So the presentation of the project may be just around the corner, as well as its release. He previously worked at Eidos Montréal on Marvel’s Guardians of the Galaxy.