Yes. It is free to download, there is nothing to buy inside it, and it shows no advertising.

How do you play NOCTULE?

Tap to flap. That is the whole control scheme. A flap is also a bat's echolocation call, so it lights the cave ahead in an expanding wavefront that then fades. Glide and you keep your altitude longer but the map goes dark; flap and you can see, but you climb. The run does not start until your first tap.

Can I play NOCTULE in a browser?

Yes. This page runs a playable cave built on the game's own physics, cave generator and pixel renderer, so you can try the mechanic without installing anything. The phone game is the full version, with sound, six colour schemes and the global top 100.

Is NOCTULE on Android?

Not yet. The Google Play release is coming; the iPhone and iPad version is out now on the App Store.

Does NOCTULE need an account or an internet connection?

No account, and it plays entirely offline. The only thing that ever leaves your phone is a run good enough for the global top 100, which goes up under a short name you can change whenever you like.

Why does the cave get darker the further I go?

Because it is meant to. The difficulty ramp narrows the corridor and speeds the cave up, and it also shortens how long a lit surface stays lit — from 0.86 seconds at the mouth down to 0.7 at full difficulty. You are not seeing less because you are worse; there is less to see.

NOCTULE — a one-tap echolocation flyer for iPhone

The whole game

You are a bat in a dark cave

Tap to flap. That’s the whole control scheme. But a flap also echo-locates, throwing a wavefront out ahead of you that lights the rock it touches, and then fades. Stop flapping and you keep your altitude a little longer, but the cave goes dark around you. Flap to see, and you hit the ceiling you just lit.

That’s the game. Not just “avoid the obstacles” — decide, several times a second, whether you would rather know where you are or be where you want to be.

Anatomy of one call

The flap is the light

One tap does three things at once, and they pull against each other. It sets your upward speed — it does not add to it, so a rhythm of small taps flies flatter than one big one. It costs you the choice of staying low. And it calls: a circle of sound leaves the point you were at, travels outward at 258 units a second, and lights whatever surface it crosses.

The light it leaves is not a lamp. Each lit patch of rock starts at full brightness the instant the wavefront reaches it and fades to nothing over the next 0.86 seconds. Near walls light before far ones, because the sound gets there first. Everything you can see is a memory.

One call, at a fifth of speed. At the real rate it is over in a quarter of a second.

No download, no install

Fly it here

This is the real thing, not a video: the same physics, the same cave generator and the same pixel renderer the phone game uses, ported to the browser. Tap or click the cave to flap. One hit and you are done.

Deep 0 Calls 0 Best 0

The phone game is the full one: sound built from the flight itself, six colour schemes, and a global top 100. Get it free on the App Store.

The difficulty ramp

The deeper you go, the darker it gets

Most endless games get harder by giving you less room. This one does that too — and it also takes the light away. Drag through four kilometres of cave and watch the numbers move. The plate underneath is the cave that actually exists at that depth, flown by the same engine, not a drawing of the idea.

Only one of the three falls in a straight line. Light lasts goes from 0.86 seconds to 0.70 and never once goes back up. The corridor breathes instead: it narrows on average, but it is interrupted by chambers, which open it right out for a breather, and stabbed by pinches, which close it to barely more than a wingbeat. Drag slowly and you will find both.

Depth into the cave, in world units

Corridor: 42.7 u
Light lasts: 0.86 s
Cave speed: 60.0 u/s

At 0 units in. Nobody has to explain this to you — you feel it happening.

On a phone

What it looks like

One run, start to wall.

The cave is drawn as coarse pixels on a lattice, four palette steps deep, and brightness is the whole hierarchy — the brightest thing on the screen is always the thing that just answered you. There is no type in the game that is not built from the same 3×5 table the walls are drawn on.

When you hit something the cave floods with light for a moment and you finally see all of it: the shape of the thing that killed you, and how close the way through really was.

Title
One call
The wavefront
The moment
Where it ended

What you get

The short version

Controls: One tap. Constant gravity. One hit and it’s over.
Price: Free. No advertising, no in-app purchases, nothing to unlock.
Account: None. Nothing to sign up for and no email to give.
Offline: Plays entirely offline. Only a top-100 run ever leaves the phone.
Sound: Built from the flight itself — the wingbeat sets the tempo.
Colour: Six schemes, if violet is not your dark.
Leaderboard: A global top 100. Beat the hundredth best and you are on it.
Platforms: iPhone and iPad now. Google Play coming.

Questions

The ones people ask

Is it free?: Yes. It is free to download, there is nothing to buy inside it, and it shows no advertising.
I die immediately when I start.: You shouldn’t — the world is frozen until you tap, so nothing can kill you before you have touched the screen. If the bat is falling after your first tap, that is gravity, and the answer is to tap again sooner: a flap sets your upward speed rather than adding to it, so a rhythm of small taps flies flatter than one big one.
Can I play it in a browser?: You just did, further up this page. It runs the game’s own physics, cave generator and renderer. The phone game is the full version: sound, six colour schemes, and the global top 100.
Is it on Android?: Not yet. The Google Play release is coming. The iPhone and iPad version is out now on the App Store.
Does it need an account or a connection?: Neither. It plays entirely offline. The only thing that ever leaves your phone is a run good enough for the global top 100, which goes up under a short name you can change whenever you like. The privacy policy is the long version.
Why does it get darker the further I go?: Because it is meant to. The ramp narrows the corridor and speeds the cave up, and it also shortens how long lit rock stays lit — 0.86 seconds at the mouth, 0.7 at full difficulty. You are not seeing less because you are worse. There is less to see.

Take it with you

The cave fits in a pocket

Every run kept, the sound on, and a hundred people ahead of you to chase.

Google Play coming soon

Free. No advertising, no purchases, no account.