"Never get out of the boat," says Captain Marlowe in Apocalypse Now. "Not unless you're going all the way." It turns out this is just as true of a submarine, and especially at night, 300 metres below the surface. I'm on my way back to base from a salvaging trip, hold packed with lithium from shale deposits on the edge of the reef. The sub - a chubby, whirring frisbee with a bubble cockpit - has taken a few knocks while rooting through the trenches, and in a moment of great wisdom, I hop out to perform some repairs. It's not an entirely idiotic decision. The sea floor ahead is thick with towering ferns that provide cover for a species of coyote-like predator, whereas right here I can see nothing save schools of fish the size of my thumb, twisting in the dark like flurries of snow. In hindsight, the absence of larger fauna really ought to have set a few alarm bells ringing, but all I can think of are the scratches on my Seamoth's lovely yellow finish. Besides, I've got two health packs left, and a fancy thermo survival knife that cooks anything you hit with it. The water holds no fear for me.
I've barely aimed my repair gun at the sub when there is an almighty crunch and it vanishes. Turning, I glimpse the vessel's headlights spinning wildly through the blackness, and in the glare from those headlights, a corkscrew motion and the flash of dense, milky-white flesh. Whatever it is, it's so big that I can't see all of it. There's another horrible metallic screech and the Seamoth is released, to dangle sadly in a halo of debris and spurting gas a hundred metres off. Swimming over to it takes approximately ten seconds and thirty million years. Scrambling inside with my heart in my teeth, I hastily switch off the lights and check the sub's hull strength. Five per cent. The water around me is utterly still. All the same, I decide to head back to the shallows before attempting further repairs.
Terror, wonder, and a generous whack of underwater DIY. This is Subnautica in a nutshell. Available in feature-complete form this week after three years on Steam Early Access, Unknown Worlds' impressive survival sim casts you as a lowly but very able crewman aboard the starship Aurora, sometime in the late 23rd century. As it begins the Aurora crash-lands on a remote waterworld following a mysterious explosion. Regaining consciousness, you find yourself adrift in a damaged escape pod, the Aurora's enormous, burning carcass the only thing visible on a balmy blue horizon.
