Subnautica: Below Zero empowers the player with more gadgets and narrative momentum, but still makes you feel like a drop in ocean

I'm approximately 500m below sea level, ferrying an underwater Seatruck - now stacked with precious materials harvested from a nearby crater - through a maze of rock and ice, desperately searching for an exit to the surface. There's a noise to my left; a thunderous, bassy roar. 

Switching off the Seatruck's electrics, I hop out of the pilot seat and peer through a window on the port side. It's a Shadow Leviathan, one of Subnautica: Below Zero's new apex predators, and he's apparently decided my ship will make for a tasty afternoon snack. Desperate to keep hold of my precious cargo, I boot the engine back up and attempt to make a break for it, but it's too late: the eldritch sea demon has latched his tendrilous maw around the cockpit, spewing acid over the windscreen before the entire vehicle blows up in its mouth. 

Half-dead from the explosion, I gaze around at the wreckage of my pursuits in dismay. There's at least an hour's worth of quality subaquatic spelunking scattered across the seabed, but it's the least of my problems right now, as the Leviathan's spindly, neon-blue mouth turns its gaze towards me. Oh well, there's always next time.  

Frozen planet

It's stories like these that are the best illustration of what Subnautica has always been about - survival and scares amidst the deep blue backdrop of alien waters - and its standalone expansion, Below Zero, has every intention of maintaining that inimitable sense of immersive dread. 

"Water is inherently terrifying", says project lead David Kalina of Subnautica's uniquely submersive brand of survival horror. "Drowning is a primal fear, so right at the start the very first survival mechanic makes immediate sense for anyone playing it. The dangers of being underwater is something our lizard brain just gets. There's an existential risk that's really immediate."

But Below Zero isn't just delivering the same package in a different skin. Instead, Unknown Worlds hopes to address areas of the original Subnautica where choppy waters would sometimes undermine the player experience. For one thing, the studio is aiming for what it calls a "story forward narrative", where plot remains a key driver to your time playing as new protagonist Robin. Whereas Subnautica's unravelling mystery was all 'show, don't tell', Below Zero has dedicated voice acting, scripted sequences, and even the odd cutscene or two. Kalina explains that this came from "a desire to avoid repeating ourselves and push into new areas of direction".

"Story was something that was added pretty late to the first game," he tells me, "and we didn't get to push as far as we'd have liked to with it. So from the very beginning [of Below Zero's development], it was an area that the team was interested in exploring more - creating a story that's alive, as opposed to just baked into the environment. It becomes a much bigger challenge to mix those different story elements together; the background lore along with the more immediate conflict of trying to talk to this alien stuck in your brain!"

Oh, sorry, did we not mention that you have an ancient extraterrestrial living inside your head in Below Zero? It's the key driver of the expansion's plot, in which a mysterious hyper-advanced entity hijacks Robin's mind after she accidentally awakes it from slumber, and the pair must work together to help it find a more suitable host. You're thus no longer merely trying to escape Planet 4546B in Below Zero, as you were in the original game. Robin has purpose and personality, and Unknown Worlds wants to make sure those two things bleed into all aspects of gameplay. 

If the title wasn't something of a giveaway, Below Zero is also set in a much cooler region of Planet 4546B than the ocean we dropped into last time, and this environmental shift has an equally transformative effect on its survival horror rhythms. Not only are there an aquarium's worth of new fauna and flora to harvest, run from, or merely observe, but Unknown Worlds has introduced a number of special tools and gadgets with which to explore and study its frozen biome.

There's the aforementioned Seatruck, an underwater train that can be extended with an unlimited number of carriages, or the Snowfox hoverbike, which can glide across the ice at great speeds - perfect for escaping the aggressions of any nearby Ice Worms. Underwater base building has also been enhanced, with more options for customisation and expansion, while Kalina confirms that a Creative mode will be included with Below Zero's full launch for those who prefer building free from the limitations of its survival mechanics.

Down where it's wetter

None of this will come as a surprise to those who've already been playing Below Zero, of course. Operating in open development, Unknown Worlds has been working with an active community of players in Early Access since 2019, but the team is now preparing for a full launch across PC, PS4, PS5, Xbox One, Xbox Series X, and Nintendo Switch this Spring. According to Kalina, the decision to finally bring its latest water baby out of Early Access hasn't been an easy one to make. 

"We've moved our release date internally many times," he admits. "You just have to make a decision at some point and draw those lines in terms of features and content. That's one of the tricky things about sharing our progress, players can get attached to concepts that we ultimately move on from. So, yeah it's been a little bit of a tightrope, but the story has helped frame Below Zero and allows us to draw those boundaries."

The result of that tightrope walking is hopefully a survival horror experience that's a little tauter and pacier than its predecessor, but no less immersive or compelling, both in and out of the water.

For more, check out our list of the best horror games to play right now, or watch the video below for our full review of The Medium.