Paahu
Bring a coral reef to life.
Uses DDAP Sigil
Paahu is a calm game about bringing a dying coral reef back to life. You start on a quiet, struggling reef: pale coral, broken rubble and a warm volcanic seep, with small fish passing through, looking it over.
Draw currents to feed the coral, steer the vent's warmth, and watch the reef rebuild itself and fill with life. Paahu is the Hopi word for water, and the game points you to the people protecting real reefs.
Water Is Life
Paahu is the Hopi word for water, and for a spring: one word for both. For a people of the high desert, little is more sacred.
The Hopi word for the ocean, Paatuwaqatsi, also names a central Hopi principle: the water that sustains all life, often given in English as “water is life.” That idea is the heart of this game.
Here, you help a reef grow and watch life return. Real coral reefs cover less than 1% of the ocean, yet they provide food, shelter and nursery grounds for nearly a quarter of all ocean species.
When the water stays too hot, coral loses the tiny algae that feed it and turns white: it bleaches. If the heat passes in time, it can recover; if the heat lasts, the coral starves. From 2023 to 2025, heat strong enough to bleach coral reached 84% of the world’s reef area, and mass bleaching was documented in at least 83 countries and territories. The IUCN now counts nearly half of all warm-water reef-building coral species, 44%, as threatened with extinction.
People are working to give reefs a future: protecting them, cleaning the water that reaches them, growing and replanting coral, and tackling the warming itself. Meet some of them below.
How to Help
Learn more, volunteer, or support their work:
Coral Reef Alliance
Working with communities to reduce the threats reefs face, so they can adapt.
coral.orgCoral Restoration Foundation
Growing coral and replanting it on reefs in Florida and beyond.
coralrestoration.orgReef Check
Training volunteer divers to survey and protect reefs worldwide.
reefcheck.orgThe Nature Conservancy
Protecting reefs worldwide, and training the people who look after them.
nature.orgSECORE International
Breeding coral from its spawn and seeding young corals back onto reefs.
secore.orgGreat Barrier Reef Foundation
Protecting and restoring the world’s largest reef system.
barrierreef.orgWildlife Conservation Society
Protecting the reefs most likely to survive warming seas, with the communities who depend on them.
wcs.orgInternational Coral Reef Initiative
Governments and organizations working together to protect the world’s reefs.
icriforum.orgNOAA Coral Reef Watch
Watching the oceans’ heat from space and warning of bleaching.
coralreefwatch.noaa.govIUCN
The global authority on the state of nature; its Red List tracks which corals face extinction.
iucn.orgHow It Plays
Draw the Currents
Drag a finger through the water to draw a current that carries plankton down to the pale coral, where it feeds and heals. Tap to send out a ripple.
Keep It in Balance
Steer the vent's warm water over healthy coral and the reef becomes a place fish want to live. Too much warmth bleaches coral, too much food grows algae, and too much stirring clouds the water, but healing is quicker than harm and nothing is ever lost for good.
A Reef That Builds Itself
As it heals, the reef builds itself up, as real reefs do: under healthy, mature coral the rock rises into mounds and the coral grows on top. More than a dozen kinds of coral, each in its species' real colours: staghorn, table, brain, boulder, flowerpot and hammer corals, leather corals and sea fans.
Life Moves Back In
Each creature arrives when its home exists: chromis and anthias, butterflyfish, tangs and Moorish idols, Clark's anemonefish, a cleaner shrimp, giant clams that shut when a shadow passes, a pufferfish that puffs up at a tap, an octopus and a moray. Look closer for a lionfish, a frogfish or a shy mandarinfish.
Bigger Visitors
On a reef grown large, bigger visitors come in their turn: reef squid, reef sharks, barracuda, dolphins, a manta, hammerheads, a dugong grazing the seagrass, a whale shark and, very rarely, a humpback whale far off.
A Reef Without End
Drag with two fingers to move along the reef. Beyond the coral lie golden Sargassum, kelp forests with seahorses and seadragons among the fronds, clam beds, pinnacles, arches, a deep trench and an old wreck on the sand.
The Field Guide
Everything you find goes into the field guide, with its scientific name, size, home, diet, three things about it and how it is faring on the IUCN Red List. Press and hold to scatter food for the fish, and take a clean picture of your reef to keep or share.
Calm by Design
Drawn from real Indo-Pacific species in soft underwater light, with the sound of the water, singing bowls and a kalimba note each time coral catches its food. No timers, no lives and no way to lose; HOW TO PLAY shows you the way in.
Leaderboards and Achievements
When you leave, put the reef to bed: its living coral goes to the leaderboards, with your friends first and then the world, and achievements mark what it has become. While you are away the reef keeps growing. Leaderboards are optional; the reef plays fully without them.
Screenshots
Phone
Tablet
Privacy
Your reef is stored on your device. Leaderboards and friends are optional and use an anonymous DDAP Sigil: a random ID, the gamertag you choose, and your game results. No name, email, phone number or location is collected. Data is never sold, never used for advertising, and never used to track you, and you can delete your Sigil and all of its data from inside the app at any time. Read the full privacy policy.
Join the Paahu Beta
Paahu is in private beta for iPhone, iPad, and Android phones and tablets. Testing is by invitation: tap Request Beta Access below and fill in the short form in the email: your device, operating system and version, and the Apple ID or Google account you use with the App Store or Google Play. Test invitations are tied to that account, so please use the one on your device.
Paahu is free, with no ads. No account is needed to play.