Bone Comb

Crypt of the NecroDancer is the dungeon crawler where the dungeon is on a metronome. You get one action a beat, everything down there gets its own cadence, and the whole game turns out to be about reading those cadences four beats ahead rather than about reacting to anything. It came out in 2015 and nothing has really improved on the idea since.

This is that shape, one screen and one sitting. It is an homage and it says so. Nothing is lifted — every tile, foe, weapon and noise here was written from scratch — and it is not connected to that game or its studio in any way.

Calibrate first, once#

The very first Start opens a metronome, not a crypt. Tap along with it twelve times and the cabinet learns how far behind the beat you are — your speakers, your screen and your hands together, which on a Bluetooth speaker is most of a beat and on a wired pair of headphones is nearly nothing. That number is then taken back out of every press you make, so a player who is consistently forty milliseconds late is simply on time.

It is the thing the genre has done since the first of these games and it is not ceremony: the accept window at 174 BPM is 86 milliseconds wide, and half of it can be gone before you have pressed anything. Every screen after this one is a timing judgement, and until the number exists they are all being judged against somebody else's hardware.

• It is asked once per browser. The answer is remembered; `C` on the shelf asks again, which is what you want when the headphones change.
• It is skippable. `↵` leaves it and the beat is judged raw, which is what it always was.
• It costs the run nothing. No clock is running on it, exactly as with the shelf below.
• It moves the judging, not the crypt. The dead still move on the record's own beats. Shifting the world by your latency would move them off the song.

Pick a record next#

Start opens the shelf, not floor one, and the first thing on it is the soundtrack this game is an homage to.

The NecroDancer soundtrack, a track a floor#

Danny Baranowsky's score for Crypt of the NecroDancer, off his own channel, twenty-four tracks, one per floor. It is what this cabinet plays unless you tell it otherwise, which is the right way round: an homage that played its own chiptune loop instead of the thing it is an homage to had it backwards.

• The mapping is the zone ladder, and it lines up for free. That game's zones are three levels and a boss; a queen holds every fourth floor here. So floors one to three are 1-1, 1-2 and 1-3 in the order you meet them down there, floor four gets King Conga, and every boss floor after it gets a boss theme.
• The tempo is the track's, so the difficulty is the album's. 115, then 130, then 140 — and then it resets at each new zone, exactly as it does in the original. A beat is an action and the accept window is a fraction of it, so floor 8 at 175 BPM is a harder floor than floor 9 at 135, and that is the shape of the record rather than a curve anyone here drew.
• The change happens on the floor, not between runs. Step into the hole down and the next track is already loading; the beat grid re-lands on the new record's own beats without moving the beat you are standing on, and the seam is forgiven rather than counted as a missed beat.
• The tempos were not guessed. They are the NecroDancer wiki's own table, which is a design document rather than an estimate — that game's grid is its tempo — and each was cross-checked against the length of the upload it is played from.
• Every id was checked against YouTube's own player data for whether it will actually play in an embed, because a link that is embeddable on paper and refused in practice is a failure in front of the player, and there are twenty-four of them.
• A browser whose YouTube player will not answer plays one track the whole way down. With no player there is no clock on the record, so the only thing a swap could anchor the beat to is the moment the request was sent — and at 140 BPM the buffer fetch alone is most of a beat. One track in time beats twenty-four out of it.

Or something else#

Under the soundtrack are six other records, each with its own tempo written down, running from 113 BPM to 174 — and because the accept window is a fraction of the beat, that list is also a difficulty select.

Under those are the house tune and your own link: any YouTube video, and the crypt keeps time to it. Most of the time that is the whole of it — the deck works the tempo out for itself.

• The tempo comes off the link when it can. A huge share of what anyone brings to a rhythm game says the tempo on the tin — HARD TECHNO 150 BPM, @174, (128bpm) — and the deck reads it straight out of the video's title. When it is there, you pick the record and go down and nothing else is asked.
• When it is not there, you tap it once. Going down opens a find the beat screen with the record already playing: tap along eight times with any key, and it locks the tempo and the sync off your taps. It is never asked again for that track. A bare number is never guessed at out of a title — Top 100 Hardstyle 2024 is not 100 BPM, and a confidently wrong tempo is worse than none.
• The beat runs while you choose. The strip along the bottom of the shelf is the record's own beat, not a placeholder, so you can see whether the sync is right before spending a run on it. `T` taps it into line and `[` and `]` nudge it, both from the shelf and mid-run.
• The tempo has buttons, because typing is the wrong instrument for it. `−` and `+` walk it a beat at a time — which is what you do when the strip drifts slowly against a title that rounded 126 to 128 — and `,` and `.` halve and double it, which is the single most common wrong answer anywhere near a BPM. Half time and double time are the same song, so a drum and bass track read as 87 is one press from right. All four are on the deck as buttons and on the shelf as keys, so the hand watching the strip never has to leave it.
• Nobody can do better than that, and it is worth saying why. A web page cannot listen to the audio inside a YouTube embed. Not with a trick, not with permission, not at all — the sound is in another origin and no analyser can reach it. So the tempo either comes from the words next to the video or from you, and anything claiming to have detected it would be lying about where the number came from.
• A track is tuned once. The tempo and the sync are remembered against that video, so the next time you put it on the deck already knows the answer and going down is the only thing left to do.
• Nothing is sent to YouTube until you press Load. No iframe, no script, no request. Press it and the embed is the no-cookie one.
• A record that will not start says which half failed. If the embed never arrived, that is a content blocker refusing it and the deck says so — allow `youtube.com` and `youtube-nocookie.com` on this site and press Retry. If the embed arrived but YouTube's player never answered the page, that is a different fault and there is a Play it anyway button for it: the record plays, you tap the beat, and the crypt keeps time to your taps instead of to the video's clock. Either way it drops back to the house tune rather than sitting on Loading the record… forever.
• A browser that fails that handshake is only asked once. Whatever causes it — an extension, a privacy setting — it is a property of the machine and not of the video, so the deck writes it down and takes every later link straight to playing blind instead of spending the wait again. Try full player puts it back, and a handshake that does succeed clears the verdict by itself.
• Tempo is clamped to 70–190. Not taste: a beat is an action, so the tempo is the speed the whole game runs at, and the scoreboard's limits are worked out from the top of that range. A faster song is not a higher score — the accept window narrows with it.

The house tune is a synth loop at 124 BPM, and it is the one thing down there this cabinet actually owns. It is also the fallback rather than the default now: everything else on the shelf is somebody else's record playing in YouTube's own embed, exactly as it would on any other page that links to it, and if YouTube cannot be reached the house tune is what the crypt keeps time to.

One action a beat#

Step, dig, swing, or hold — all four are the same thing as far as the beat is concerned, and you get exactly one of them per beat.

• Walking into something is how you hit it. There is no attack button. The direction you press is the direction you swing.
• Holding is a move. `Space` spends the beat standing still, which keeps the chain alive. Waiting for a husk to walk into range without losing four rungs of multiplier is a real decision and it is what the key is for.
• Off the beat is nothing at all. Press between two beats and the bee does not move and the chain breaks. The window is a fraction of a beat, so it is generous at 80 BPM and unforgiving at 180.
• The floor keeps time. Which half of the checker is lit swaps on every beat and the lit half brightens as the beat lands, so the comb under you is a metronome the size of the screen. The downbeat of each bar is gold and the other three are violet, which makes a bar countable without looking anywhere — and four is the length of every cadence down there, so a player who can see the bar can see when the wight moves.
• The ring around the bee is the beat too. It contracts onto her as the beat arrives, and the strip along the bottom shows the next six coming. All three are readable with the sound off, and the floor is the one that is where your eyes already are.

Every eight unbroken beats is another rung on the honey multiplier, up to ×5 — six with the amber ring. Honey is the only thing the multiplier touches — a kill is worth what it is worth — so the chain is what turns a floor you cleared into a floor that paid.

A different dancer every floor#

The crypt is the same crypt all the way down. Who is reading it is not. Every floor is held by one of nine dancers, and each of them bends a rule this cabinet otherwise never bends — so a run is not one game got harder, it is nine games in the order the bag deals them.

That is the one idea this homage takes from the game it is an homage to and could not have been an homage without. Crypt of the NecroDancer's characters are not difficulty settings: Aria dies on a single missed beat, Dorian's boots steer him backwards, Bolt runs the whole soundtrack at double speed, and none of them is the same game with a number turned up. It is the best idea in that game and the reason people are still playing it eleven years later.

• Floor one is always Harrow, who bends nothing. A first floor should be the game this page has just finished describing; the second is where the cabinet says what it actually is.
• Everything after it comes out of a bag, so a run never draws the same ruleset twice running and a deep one meets all nine before it meets any of them again.
• The rules are on the card the floor opens with, under her name, and the name stays in the status bar for the whole floor after the card has gone. Two lines is the budget on purpose: a rule you cannot hold in your head while you take the first step is a rule you will play as if it were Harrow's anyway.
• None of them touches the score. Not taste — the scoreboard's limits are worked out from the tempo, from the twenty-four steps the stairs are promised to be away and from the twenty-two things a floor can hold, so a dancer who paid double would be a dancer whose good runs the board refused. What they change is how a floor is survived, never what it is worth.
• A queen does not get a floor off. Every fourth floor is a queen's and somebody's, so the Pale Empress under Vesper is a boss fight held one tile at a time.

Reading the dead#

Nothing down here has a projectile, so every hit you take is one you could have seen a beat earlier. What separates them is when they move, and everything rises on the beat before its own. Sixteen of them, arriving a couple at a time as you go down — the floor banner says which ones are new.

Four queens#

Every fourth floor is a queen's, and there are four of them taken in turn — one boss met four times in a deep run is the same fight four times, and this cabinet's whole subject is reading a cadence. She is also standing on somebody's floor: a queen under Fever is the same queen at double time, and one under Knap is a queen fought with the bone dagger.

None of them stands on the hole down. It is open the whole time they are chasing you, so walking past a queen is always a real choice: five hundred against the hearts it costs to take her.

The four weapons#

Reach, not damage. Which one is in hand decides which beat you can afford to be standing where you are.

A weapon is guaranteed on every second floor rather than left to the roll, because a weapon is the only thing down here that changes which beat you can afford to be standing where you are — and on the old cadence the median run ended holding the dagger it started with. Knap's floor takes it off you for the length of that floor and hands it back at the bottom, which is the one place the ladder pauses.

What a floor hands you#

Two or three pick-ups a floor on top of the weapon, off a bag weighted by what the run has not got: a heart is nearly the worst thing on the floor at full health and the only thing on it at one. None of them touches the score, so what you are carrying is a question about surviving rather than about the board.

Digging is a choice about time#

Wax is diggable and stone is not, and the way down is never fewer than twenty-four steps from where you land. That is the whole map decision: the rooms and corridors are the fast route, and everything else is a route you pay beats for.

The honey buried in the wax is the reason to pay them. So is the fact that a corridor is where a wight catches you and an open room is not.

Posting a run#

Sign in with Discord and the run posts itself when the last heart goes; play as a guest and it is kept as a personal best on this device instead. The board ranks on score and shows the floor you died on beside it, because that is the number people quote. Clearing floor N pays N × 150, so the run is worth almost exactly how deep it got. The arcade page has the longer version of how the boards work, and the other cabinets.