Originally Subnautica was intended for Co-op play, however to release the game faster Unknown Worlds opted for single player, of course with the intention to release a later update for Co-op. After the release of Subnautica, their team realized they would have to restart the process from the beginning in order to add Co-op which would pull focus from enhancing the game as is. With this in mind, they decided no Co-op development would happen and Subnautica would remain single player. However Unknown Worlds, did say they they intend to release a later version of Subnautica, similar to what Klei did with Don’t Starve, and that this release game would support Co-op play.

So my question would be, What happened? Did something change, do you not believe survival games would be enjoyed with the ability of Co-op play? Their have been several survival games released that support Co-op and a lot more that are only single player, that would be improved with Co-op support.