Horizon Deep: Idle Abyss

Horizon DeepA text-based deep-sea RPG for iPhone and iPad

You wake cold on a research station at the bottom of the sea. The lights are failing, the air is thin, and something in the dark below is singing: three notes, patient as the tide. Bring the drowned station back to life, wake its crew, and dive the black water around it on sonar.

Download on theApp StoreFree to download · optional Chapter II unlock

No ads. No account. Plays offline, and keeps going while you are away.

A pale deep-sea creature with a gaping, needle-toothed mouth, drawn in teal on black: art from Horizon Deep
Horizon Deep on iPhone: the sonar scope during a dive

What you do

A slow-burn idle RPG at the bottom of the sea

It starts as one instrument on an empty screen and quietly opens into a whole abyss: a station to keep, a crew to feed, a seafloor to chart and a signal to follow.

Reclaim the station

Pump out flooded compartments one by one. Install fabricators, galleys and gardens, and wake a crew of named survivors, each with a knack, to keep it running. The station is a sealed pressure vessel, and the sea keeps trying to get back in.

Orin mended clocks, once. Pressure makes every clock lie down here, they say, so they stopped wearing one.

Dive the dark on sonar

Trace the seafloor on a live sonar scope with your finger: a slow, drifting swim through currents, wrecks, scalding vents and predators you read on the scope and route around, or turn and fight. Your air is your range, and only what you carry back through the lock comes home.

The tank is nearly dry. Your lamp gutters. Above you, a light in the black water. The station.

Follow the signal

Recover strange relics and study them in the survey lab. Crawl the flooded insides of derelict hulks, chart named places on the shelf, and piece together why three notes keep rising from below. Then choose how to answer them.

The heart hangs open like a door, warm brass and older than language.

New in 1.2 · Chapter II

The Other Heart

With the seam answered, the second signal comes in whole. Far north, under the ice, a second station, and a heart beating wrong. Someone there is still alive.

  • Dive between pockets of air beneath the ice.
  • Follow the voice on the radio to where it comes from.
  • Find what the builders left, and answer the second heart.
  • An aurora theme for the sonar, in both chapters.

Chapter II opens once you have answered the signal at the end of Chapter I. Its first act, waking under the ice, is free. The rest, from the first dive under the ice, is a one-time unlock. No subscription, and Chapter I stays complete.

A diver with a lamp climbing down the cliff of a deep trench, drawn in teal on black: art from Horizon Deep

Good to know

Offline, unhurried, and what it costs

  • No ads, no accountNothing to sign up for and nothing in the way. The story is told in a station log, not cutscenes.
  • Plays offlineFully playable with no connection. The station keeps working while you are away, up to eight hours at a time.
  • Free to downloadChapter I is complete and free. Chapter II opens free; the rest is an optional one-time unlock. An optional tip jar unlocks nothing.
  • Your save, your iCloudSaved on the device and mirrored to your own iCloud, so a new iPhone or iPad picks up where you left off.
  • Home-screen widgetKeep an eye on the station from the home screen, in a small or medium widget.
  • iPhone and iPadiOS 17 or later. In English and Japanese. Rated 4+ on the App Store.

A closer look

Horizon Deep screenshots

Horizon Deep dive screen: a round sonar scope with the diver at the centre, wrecks and kelp marked around it, and air, blood, rations and haul counters below
The dive: trace the seafloor on sonar
The Horizon Deep station screen: a porthole view above a grid of compartments such as berths, gardens, galley, fab bay and lab, with Harvest the kelp and descend buttons
The station: compartments brought back online
A transmission in the Horizon Deep log: the crew finds a photograph of a crowded pier in a sealed bag, with the choice Pin it in the galley
The log: a story told in short lines
The opening of Horizon Deep: a small sonar ring in the dark and the text The tank is nearly dry. Your lamp gutters. Above you, a light in the black water.
The opening: swim for the light
The seam in Horizon Deep: a glowing heart at the bottom of a stairway and three choices, Mend it, Silence it and Step inside
The seam: choose how to answer
Horizon Deep on iPad: the station with its compartments, holds, the logbook and the descend button in one column
On iPad, the same station with room to breathe.

FAQ

Questions about Horizon Deep

What is Horizon Deep?

Horizon Deep (on the App Store as "Horizon Deep: Idle Abyss") is a text-based deep-sea idle RPG for iPhone and iPad. You wake on a failing research station at the bottom of the sea, pump out its flooded compartments, wake a crew of named survivors, and dive the dark around it on a sonar scope, following a signal of three notes from below. The story is told in short lines in a station log, not cutscenes.

Is Horizon Deep free?

It is free to download, with no ads and no account. Chapter I is complete and free. Chapter II, "The Other Heart", opens for free too; the rest of it, from the first dive under the ice, is an optional one-time unlock. There is also an optional tip jar that unlocks nothing. There is no subscription.

Does it play offline?

Yes. Horizon Deep plays fully offline. The station keeps working while you are away (up to eight hours at a time) and the log tells you what happened when you come back. The only things that use the network are the optional anonymous play stats, which you can turn off, purchases through the App Store, and iCloud save sync.

What is Chapter II?

Chapter II, "The Other Heart", is a second station under the ice, with a voice on the radio and dives between pockets of air. It opens after you have answered the signal at the end of Chapter I. Its first act is free; the rest is a one-time unlock that also adds an aurora theme for the sonar in both chapters.

Which devices and languages does it support?

iPhone and iPad running iOS 17 or later. The game is in English and Japanese. It is rated 4+ on the App Store.

Will I lose my station if I change phones?

No, if iCloud is on. Your save is stored on the device and mirrored to your own iCloud, so a fresh install on a new iPhone or iPad signed in to the same Apple account picks up where you left off. The Chapter II unlock comes back with Restore purchases.

Descend carefully

The charts end where the dark begins. Horizon Deep is on the App Store for iPhone and iPad: free to download, with an optional Chapter II unlock.

Download on theApp Store

Support

Questions, a lost station, trouble with a purchase?

Horizon Deep is made by one person, and every message gets read. Email awlabsdev@gmail.com, or see Horizon Deep support for restoring Chapter II, iCloud saves and the play stats setting.

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