Aurora — the sky that sings

Lumi

The creature in the middle of the sky is the instrument’s voice: moving it changes the character of every note.

Drag left or right changes the kind of sound: on the left it is round and soft like a flute, toward the middle fuller and buzzy, on the right stranger, almost a voice, up to a bell. Lumi’s shape and colour change too, and so does the colour of the sky.
Drag up or down changes the brightness of the sound: up high it is clear and bright, down low dark and muffled, as if heard from behind a door.
While it moves Lumi hums the last note you played, so you hear the change at once. You can also touch an empty part of the sky: Lumi flies there.
A short tap on Lumi makes it sing: a random melody, different every time (if nothing else is already playing).

For the curious: left and right move the position in the wavetable, eight waveforms that blend into one another (Lumi’s outline is the wave that is playing). Up and down open and close a low-pass filter: cutoff frequency, with a little resonance halfway along.

The crystal keys

These are the white notes of C. A computer shows fifteen of them, two octaves, from C2 to C4, including C4. A tablet shows an octave and a half, from G2 to C4. A phone shows one octave, from C3 to C4, so the crystals stay large. The lowest are on the left, the highest on the right. Hold one down and the note continues; you can press several keys at once, even with more than one finger, and slide a finger from key to key. Each note sends a little light to Lumi and lights up the sky.

On the Mac keyboard you play with two rows. The low octave, C to B, is the bottom row: Z X C V B N M. The high octave, C up to middle C, is the middle row: A S D F G H J K. On a tablet or a phone, only the letters of the crystals on screen remain, starting from the left.

For the curious: it is the C major scale, the white keys (C, D, E, F, G, A, B), from C2 to C4 inclusive. Up to eight notes can play at once.

The cloud

It decides how each note begins and how it fades. Each tap changes the weather: stars, snow, drops, then stars again.

Stars. The note starts at once and lasts as long as you hold it.
Snow. The note arrives slowly and fades slowly.
Drops. Short, bouncy notes that fall away at once even if you keep holding.

For the curious: it is the envelope (attack, decay, sustain, release) of the volume and of the filter. Attack goes from 3 thousandths of a second with the drops to 0.7 seconds with the snow; release from 0.3 to 2.6 seconds.

The pinwheel

It is the wind that makes the sound sway. Each tap adds wind, up to three gusts; the fourth tap stops it.

Still. The sound is smooth and steady.
Three gusts. The sound sways and trembles, faster with every gust.

For the curious: it is an LFO, a slow oscillator (from about 1 to 6 times a second) that moves the tone, the filter and, just a little, the pitch (vibrato) together.

The moon

It is the space around the sound. Each tap fills it a little (four phases); after the full moon it becomes thin again. The rings around it show how much echo there is.

Thin moon. A dry, close sound, as in a small room.
Full moon. A sound in a large cave: a long tail and echoes that bounce.

For the curious: it is the reverb (amount and length) together with a stereo echo that bounces between right and left (ping-pong delay). With the thin moon the echo is off.

The nest

These are Lumi’s friends. Each tap hatches an egg: a friend is born, flies around Lumi and sings along. On the fourth tap they all go back into the egg.

Three eggs. Lumi sings alone: a thin, clean sound.
Three friends. A big, wide sound like a choir, with a lower note underneath.

For the curious: it adds slightly detuned unison voices, a sub-oscillator one octave below, and a chorus effect.

The firefly jar

It records a melody and repeats it on its own, so you can play on top. It works in three taps.

1st tap. Lid up and a red light: every note played on the keys goes in as a firefly.
2nd tap. Lid closed: the melody repeats from the start and does not stop. Meanwhile you can play over it, move Lumi or touch the other objects: the sound of the melody changes too.
3rd tap. The fireflies fly away and the melody is erased. The red dot invites you to start again.

It records at most 24 seconds (then it starts by itself) and only the notes you play, on the crystals or on a connected keyboard, not Lumi’s little songs.

For the curious: it records the notes, not the audio. That is why the melody follows every change of sound.

The comet

It is the surprise: it changes everything at once, at random. It moves Lumi and chooses the weather, the wind, the moon and the friends; then Lumi sings a few notes so you can hear the new sound.

Useful when you don’t know where to start: tap until a sound you like comes out, then adjust from there. It does not touch the jar.

For the curious: it picks at random the six values that the other objects set one at a time.

The little keyboard

It appears by itself when a musical keyboard is connected to the computer, and disappears if you unplug it. There is nothing to set up. The first time, the browser asks permission to use it: just accept.

Coloured, at the start. The white keys play their own note and light the crystal of the same name. The black keys stay quiet, so they don’t repeat the note of the white key beside them. Switch by touching the little keyboard, or with the M key on the computer.
White and black. It plays the key you press, black keys included. The gems sit in the gap between the crystals, in place of those keys. Another tap goes back to white keys only. The choice is remembered.

Pressing harder plays louder. The pedal holds the notes; if it stays down, after a while they switch off by themselves. The pitch wheel slides the voice up and down a little, and Lumi leans with it. Notes from the keyboard go into the jar just like the ones played on the crystals.

If the keyboard has knobs, they move the same things as the screen: the modulation wheel is the wind, brightness moves Lumi up and down, timbre moves Lumi left and right, reverb is the moon, chorus brings out the friends, and attack changes the cloud.

For the curious: it is MIDI, on all 16 channels. The wheel reaches two semitones up or down. The knobs are controllers 1, 74, 71, 91, 93 and 73. Ports marked DAW on some keyboards are not listened to: their buttons are not notes.

Keyboard shortcuts

Space: Lumi sings a melody.
←→↑↓: Move Lumi in small steps.
M: With a keyboard connected, switches between white keys only and every note.
I?: Opens and closes this guide. It also closes with Esc, with the cross, or by touching outside.
Q: Behind the scenes: a panel with the synthesizer’s real values while the game moves them. Press Q again to hide it.
P: Full screen. Press P again to leave.