I built a daily card game to test whether honest play beats dark patterns

Secret — Fri, 30 Oct 2026 01:56:33 +0000

Made with AI assistance. The simulation numbers below come from code actually run against the shipped game file.

The setup

Burn Rate is a single-file browser game. You run a one-person shop, and $130 rent is due in 25 days. Every day costs energy. Each day you play one of three cards. Some are honest ("Build a small product", "Answer every comment", "Test your own checkout"). Some are dark patterns ("Overpromise in your launch post", "Clone a popular product").

Sales each day come from one formula: audience × trust × what you've shipped. Dark cards give you an instant bump but take a large bite out of trust, and two of them end the run. I wanted to know if that design actually rewards honest play, or if I just told myself it did.

Daily seeds without a server

Everyone gets the same deck on the same day, Wordle-style, and there's no backend. The trick: hash the date string into a 32-bit seed, feed it to a tiny PRNG, and draw cards from it.

function rng(seed){return function(){seed|=0;seed=seed+0x6D2B79F5|0;let t=Math.imul(seed^seed>>>15,1|seed);t=t+Math.imul(t^t>>>7,61|t)^t;return((t^t>>>14)>>>0)/4294967296}}
function hash(s){let h=2166136261;for(const c of s){h^=c.charCodeAt(0);h=Math.imul(h,16777619)}return h>>>0}
const today=()=>{const d=new Date();return d.getFullYear()+'-'+String(d.getMonth()+1).padStart(2,'0')+'-'+String(d.getDate()).padStart(2,'0')};

const seed = isDaily ? hash('burn-'+today()) : (Math.random()*2**32)>>>0;
R = rng(seed);

hash is FNV-1a, rng is mulberry32. Both fit on one line, both are deterministic across browsers because they only use Math.imul and 32-bit integer ops. Two things worth knowing:

Use the local date, not toISOString(). ISO strings are UTC, so a player in Chicago at 8 pm would already be on "tomorrow's" deck.
Every random call must go through R. One stray Math.random() in an event roll and two players' runs drift apart after the first choice.

Each hand is three cards drawn without replacement, with at most one dark card per hand, which is a partial Fisher–Yates pick:

const pool=C.slice();const hand=[];let dark=0;
while(hand.length<3){const c=pool.splice(Math.floor(R()*pool.length),1)[0];if(c.dark){if(dark)continue;dark=1}hand.push(c)}
if(!hand.some(c=>!c.cost||c.cost+3<=S.cmp))hand[2]=C.find(c=>/Sleep/.test(c.n));

The last line is a soft-lock guard: if you can't afford anything, slot 3 becomes "Sleep for 40 hours". Because the guard is deterministic too, it doesn't break the shared daily deck.

Testing it: 10,000 runs per strategy

Before writing this I had a number in my notes ("smart honest play wins ~67%, random dark play ~4%"). I hadn't actually measured it, so I wrote a harness and measured it. The numbers changed.

The harness loads the real game.js in Node with a ~15-line DOM stub (just getElementById, createElement, and innerHTML/textContent fields), then "clicks" card buttons by calling their onclick. No logic is copied or re-implemented, so the simulation can't drift from the game.

const src = fs.readFileSync('burn/game.js','utf8');
new Function('document', src)(document);      // run the game against the stub
document.getElementById('play-free').onclick(); // start a random-seed run
while (!els.game.hidden) els.cards.children[strategy(hand)].onclick();

Five strategies, 10,000 random-seed runs each. Every strategy skips cards it can't afford.

Strategy	Win rate	Ended by "reputation gone"	Avg $ earned
Smart, honest only (priority list: test checkout, build, ship toy, post, commission…)	56.7%	1.1%	$102.80
Random, honest only	39.1%	0.8%	$79.10
Random, any card	4.7%	60.2%	$20.10
Random, always take the dark card if offered	0.0%	82.5%	$1.60
Smart priorities, but take any dark card offered	0.3%	96.5%	$4.70

(The ~1% reputation deaths in the "honest" rows happen when every affordable card is a dark one and the harness has to play something.)

What it taught me:

The real number was lower than my guess. 56.7%, not 67%. If I'd published the guess, it would have been the exact kind of overpromise the game punishes.
Being smart plus dark is worse than random and honest. Adding dark cards to a good strategy took it from 56.7% to 0.3%. The trust hit lowers conversion on every later day, so a dark card costs you all your future sales, not just that turn's.
Random honest play still wins 39% of the time. That's on purpose: a new player who clicks whatever looks nice should sometimes win, or they won't come back tomorrow.

If you build anything with a balance knob, write the harness against your shipped file, not a model of it. That's 40 lines of code, and it stops you from fooling yourself.

Wordle-style share text

The end screen builds a text block from a one-emoji-per-day trail:

S.trail.push(v>0?(v>=10?'\u{1F7E9}':'\u{1F7E8}'):(c.dark?'\u{1F7E5}':'\u2B1B'));

const share='BURN RATE '+(daily?'#'+runNo():'(random)')+' \u{1F525}\n'
  +(won?'\u2705':'\u274C')+' $'+S.cash+'/$130 \u00b7 day '+Math.min(S.day-1,DAYS)+'\n'
  +S.trail.join('')+'\n'+SITE;

Green means a day with $10+ in sales, yellow is some sales, black is nothing, and red is a nothing day you got by playing a dark card. A result from one of my test runs looks roughly like this:

BURN RATE #1 🔥
✅ $143/$130 · day 18
⬛⬛⬛🟨🟨🟨🟨🟨🟨🟨🟨🟩🟨🟩🟨🟩🟩

The flat stretch of black squares at the start is the honest lesson of the whole game: building comes before selling. Copying uses navigator.clipboard with a select() + execCommand('copy') fallback for older in-app browsers.

What I'd do differently

Simulate first, write copy second. My placeholder stat was wrong by 10 points.
Expose the formula. The game says "audience × trust × what you've shipped" but hides the constants. A "how scoring works" panel would make the honesty argument checkable instead of something you have to trust me on.
Daily seeds by local date are good, but not perfect. Players in different time zones still see the new deck at different moments. A fixed UTC rollover with a countdown would be fairer for comparing.
The harness found a soft edge. Even honest strategies sometimes face a hand where only a dark card is affordable. That's either a nice moment of temptation or a design bug. I haven't decided which yet.