Sinus Creek
Learn to read a heart rhythm by canoeing down one.
The creek runs at you. Every wall of whitewater is one heartbeat. Rate is how often the water hits you, and regularity is whether you can trust the next one.
Every stretch ends at a fork with a hand painted sign over each mouth. Whichever mouth you are in when the fork arrives is your answer. So naming a rhythm is steering, not tapping.
A wrong read scrapes the boat and goes in the log. It never costs you a life, and it never wipes your river.
Written by a nurse, for the people who have to read the monitor at three in the morning.
Free, with nothing to buy No account, no email Plays offline once installed One thumb, portrait
Swipe for more →
Screenshots
What it looks like
Six screens off a real build, captured by the game's own script.
What you will learn
21 rhythms, 11 findings, and which hand reaches where.
32 things, and every one of them is identifiable from what is drawn on screen. That is asserted by a gate in the repo, not by me: the audit fails the build if two of them can be confused by what the water shows. 28 are answered by name at a fork. The other four are the arrests, and you answer those with your hands.
Upper Creek
19 pools
Run the water and name it
One new rhythm at a time, paired with the one it gets confused with, and a cumulative pool every fifth rung. Mobitz I lands next to Mobitz II on purpose. Telling those two apart is the entire skill.
The Narrows
19 pools
What you do about it
The same water, now asking what you reach for. Thirteen answers, from watch and reassess to compressions and epi. Stability is part of the question: A-fib with RVR in a talking patient wants rate control, and the same strip in a patient who is grey and cold wants electricity.
The Braids
10 pools
The water off the main channel
Where the river splits. Paced rhythms, junctional escape, PVCs, idioventricular, PEA. PEA against a paced rhythm is a deliberately cruel pairing. Both are organised, and only one of them is perfusing. The boat is the tell.
Deep Water
15 pools
Shape, not timing
Everything upstream is timing. This is the eleven findings, and shape is the thing you cannot get from counting. The rhythm underneath a STEMI is allowed to vary, so nobody learns one silhouette and calls it potassium.
The Long Water
3 endless runs
How far can you get
Endless, in three tiers. Low water is gentle and has no end to it. High water answers back, and a wrong call changes the water under you. Flood is everything the river has, and it will get you eventually.
Those are not five campaigns. All 66 of those interleave into one route, so you meet a rhythm on Upper Creek before The Narrows ever asks you to treat it, and a pool never announces what is in it. Blocked practice feels better while you play and it does not transfer.
Every rhythm in the creek
Sinus, atrial and junctional
- Normal Sinus Rhythm
- Sinus Bradycardia
- Sinus Tachycardia
- Supraventricular Tachycardia
- Atrial Fibrillation
- Atrial Fibrillation with RVR
- Atrial Flutter
- Junctional Escape Rhythm
The blocks
- First Degree AV Block
- Second Degree AV Block, Mobitz I
- Second Degree AV Block, Mobitz II
- Third Degree (Complete) Heart Block
Wide and ventricular
- Sinus Rhythm with PVCs
- Ventricular Tachycardia
- Slow Ventricular Tachycardia (AIVR)
- Idioventricular Rhythm
- Ventricular Paced Rhythm
The four you answer with your hands
- Ventricular Fibrillation
- Torsades de Pointes
- Asystole
- Pulseless Electrical Activity
And eleven findings, which are shape rather than timing
- ST Elevation (STEMI)
- ST Depression
- T Wave Inversion
- Left Bundle Branch Block
- Right Bundle Branch Block
- Left Ventricular Hypertrophy
- Right Ventricular Hypertrophy
- Hyperkalemia
- Hypokalemia
- Hypocalcemia
- Hypercalcemia
Thirteen things the water actually shows you
rate, regularity, dropped beats, premature beats, QRS width, P wave behaviour, PR interval, flutter waves, AV dissociation, the ST segment, the T wave, the QT interval, and QRS amplitude by side. Every rhythm carries a range rather than one number, so nobody solves a strip by memorising a single speed.
How you play it
Push off
The route. 63 pools and three endless runs across the five reaches, interleaved into one order, picking up wherever you left it.
Daily Rapids
The same water for every player in the world, that day only. Built from the date, so it cannot be rerolled. Finishing it extends a streak, and going over does not break one.
Four arrests a run
No pulse and a clock. Alternating strokes are compressions, a held thumb charges, letting go delivers the shock. Every seven seconds the creek calls a rhythm check.
The library
All 32 entries, filled in by playing. Water you have never met has no door, and the criteria open only after you have read that rhythm right at a fork once.
Where the creek stops
It builds the vocabulary and none of the measuring.
You never hold a caliper to a PR interval here. There is no twelve lead view, so no axis and no localising a STEMI, and no trace in it has ever had a lead fall off or a patient shiver. Anyone who finished this game would know the rhythms, the discrimination sets and the arrest decisions cold, and would still need real twelve lead practice. Pair it with one.
It also contains no drug doses, on purpose. It teaches which hand reaches where. A game that drilled milligrams would be a drug reference with a canoe on it.
The small print, up front
It is free. Every reach, on the web and in the app. No subscription, no advertising, and nothing inside it to buy.
There is no account. No login, no email, no password. Your river is kept on your device, and it is never reset.
It works with no signal. Install it once and it runs in a basement. A game that is a white screen in a hospital stairwell is a game that gets deleted.
It sends back one thing, and you can turn it off. An anonymous record of how a run went: which water, how far, whether a call was right. Never a name, never an email. The switch is in Settings and it is called Send anonymous play data. The privacy page says exactly what is in it.
Seven switches. Sound, Haptics, Calm water, Bold signs, Left thumb, Bigger text and Captions. Bold signs puts heavier ink on every fork sign, so nothing in the game reads by colour alone. It is also playable on a keyboard.
Sinus Creek is a teaching game. It is not a monitor, it is not a diagnostic tool, and it is not medical advice. It deliberately contains no drug doses. Nothing in it should be used to make a decision about a real patient. Made by OxidativeRN in partnership with Data Divers LLC.