We got wrecked, and a giant piece of explorable Aurora wreckage is now available in Subnautica Early Access. At the same time, you may have noticed that you have lost the ability to build water filtration machines. A bug? A nefarious plot by Unknown Worlds to cause you all to run out of water? Not quite! We are steadily introducing 'progression' into the Subnautica 'tech tree.' For example, by introducing new base building elements over the course of the game, rather than offering them all up front for free. This will ideally ease learning for new players, and adds a sense of ongoing accomplishment throughout the game. Water filtration machine blueprints now require a fragment found inside the new piece of Aurora wreckage. To make this work, we had to make some technical changes under the hood: We removed the ability to build water filtration machines from any existing saved games.  

As we progress through Early Access, and add more progression to the Subnautica tech tree, you might notice other previously-free items requiring new fragments and blueprints. If it's ever unclear why an item has disappeared from your build list, pester us and we'll be sure to explain. - Hugh