Tidesong

All your life you've yearned for the deep. Then an unsigned advert offers a farm on the seabed for a single sand dollar, and at last you put on the brass helmet.

Far below the waves lies Coral Cove, a village of divers, merfolk and fishfolk gathered around the Old Coral, a great coral that has bleached white and gone quiet. Make the run-down farm your home, get to know your new neighbours, and find out what it will take to make the reef sing again.

Farming, the underwater way

• Rake the sand and grow 28 crops, from sea lettuce and nori to giant kelp, sea grapes and glowing algae.

• There's no watering down here: silt drifts over your crops every night, so mornings start with your brush.

• Four ocean currents take the place of seasons, each with its own crops, weather and festivals, all the way to snow drifting down onto the seabed in the Deep Cold.

• Raise purple urchins, spider crabs and bluefin tuna, bring up a seahorse foal you can ride, and keep a baby octopus or a googly-eyed urchin as your pet.

• Dry, press and polish your harvest in machines you build yourself, cook 28 dishes on a stove inside an air bubble, and age sea-grape wine in your own cellar.

• Build out your diving-bell home with a new wing, a glass dome and a bathysphere annex, and furnish it your way.

A village to call home

• Meet more than a dozen neighbours, each with a home, a daily routine and a story of their own: a fellow diver who never takes off her helmet, a dreamy mermaid who sings out over the reef, an old octopus chef with a twirly moustache, a gloomy blobfish librarian and a barracuda scientist in his tower.

• Win them over with gifts and conversation, and their friendship opens up scenes, secrets and stories.

• Six of them can be courted. Go on dates, propose with a ring you make yourself, and share your home.

• Celebrate two festivals every current, from Coral Spawning Night and the Seahorse Run to a lantern maze on Deepnight and the Spear Derby.

• Browse the wares of Old Maud, an ancient sea turtle who carries her market stall on her shell.

Wake the Old Coral

Gather offerings from your farm, the open sea and the deep to restore the reef section by section. With every section, a limb of the Old Coral takes back its colour, Coral Cove brightens around it and the shops fill their shelves. But even when the reef has its body back, it still needs its song.

Into the deep

• Dive into the Rift, a trench sixty levels deep. Mine ore, gather treasure and keep an eye on your air as you fend off its creatures, down past the vent fields and brine lakes into the hadal dark.

• Explore a sunken ship room by room, with locked doors to open and secrets to find.

• Spear fish through your helmet's porthole, and forage the Seagrass Meadow, the Kelp Forest and beyond.

• Upgrade your tools to copper, cobalt and gold, earn your diver certifications, and strap on Dr. Cuda's bubble jet pack.