Firelight

Survive one night in a dark room. Keep the fire alive, eat, and be careful what you let in.

A short horror-survival game in chunky pixel art. One night lasts about seven minutes and gets worse every hour; a run is up to five nights: the third and fourth in a blizzard, the fifth under a blood moon. Most first nights end in death; each death screen tells you what killed you and gives a hint. Only a night survived to dawn scores, mostly for how you got through it.

Play: https://firelight-topaz.vercel.app (desktop browser with keyboard or mouse, or a phone held sideways)

Status: playable and complete, still being polished. Five nights, three difficulties, six challenges and five endings are in. Online leaderboards (a Render + MongoDB backend) are planned but not built, so scores, challenge records and achievements stay in your browser for now.

Story

Zach made Firelight as a game for his sister: something genuinely scary that she'd want to beat. It started on 2026-10-15 as a single night in a dark room and grew, round by round, from what happened when they played it: she and Zach playtested every version, and their deaths, complaints and "that was too easy" drove each redesign (the difficulty modes, the two scare settings, nights 3 to 5, the challenges). It's built entirely in the browser with no assets: the pixel art is drawn in code, and the sound and music are synthesized live. Balance is tuned by simulation: bots play thousands of seeded runs, and an evolutionary search finds the strongest play for each mode (see Difficulty, tuned by simulation).

How to play

Key	Action
S	Stoke the fire (1 wood)
E	Eat: cooked meat if you have it, raw if that's all you have (raw fills you less and makes you sick). 1.5 s cooldown
X	Douse a blaze with blood (2 blood)
N	Music on or off
C	Cook up to 3 raw meat. It finishes on its own in about 6 s, as long as the fire is lit
G	Go out for wood (short trip)
F / Space	Burn her claws (1 wood, needs a fire), or slam the cellar hatch from night 2
R	Run back from a trip
B	Build
1–9	Dialogue choices
J	Journal (everything you've heard tonight)
M	Sound (also on the title screen; the game goes silent while the tab is in the background)
Esc	Menu, which pauses

What can kill you

Every threat has a tell and a counter. Threats arrive as the night goes on.

From	Threat	The tell	What saves you	Death
10 pm	The dark	Slitted eyes open around the room, a heartbeat starts, red creeps in from the edges. Once the fire is out you have about ten seconds	Keep the fire above smoldering. It burns down faster every hour	The dark comes in
10 pm	Hunger	A stomach growl at "hungry"; at "starving" it repeats and a dull red border closes in. Meat goes bad: raw in about an hour of the night, cooked in about three, and its count turns green when something is about to turn	Keep eating, which means traps early: at night they're the only meat, checked on every wood trip. Cook raw meat first; raw makes you sick. Salt-cured meat keeps	You starve
11 pm	The thing in the trees	A howl, and its amber eyes shining in the treeline outside the window. While you're out and it's close, a grin grows beneath its eyes	One rule: once it's close, the grin fills in four seconds, every time. Leave while its eyes are in the treeline and the grin races to half full almost at once, so you have about two. A falling howl tells you when it moves off. If it howls while you're already out, you get a moment to turn back first. Running back brings you home empty-handed	A full grin
midnight	The mimic	Real visitors' footsteps crunch through the snow before they knock. The mimic just knocks, word for word in the voice of someone you'd open for. There is only one stranger	Keep the door shut when nothing walked up	You opened the door. It was not a person
1 am	Her, at the window	She rises into the window from below the sill: a gaunt black figure backlit in red, with one huge pale eye, an empty socket, a hanging jaw and wet hair. On her first visit the glass always explodes inward, boarded or not, and from then on wind and snow blow in; through a bare frame the fire burns down faster	Board the window beforehand. Her eye watches through a gap while her hand hooks a board and pulls, to a rhythm of thuds. Burn the hand and she snatches it back in a burst of flame and smoke. Don't, and she tears every board off and drags them away. You have to board the window again (8 wood)	Bare window: she climbs in, even while you're out, and through the frame; you can't burn her back. You can still nail boards up in the last seconds

The door never opens by itself. Every knock asks you: open it, or keep it shut. Opening for the right people matters:

• The stranger knocks first. Let her in and she teaches you the rules. She hasn't eaten in days, so she needs cooked meat once: she begs three times, and the third plea is the one that counts. Feed her earlier and she'll be starving again before dawn. Feed her raw meat and it kills her. If she starves, something starts moving under her skin. Drag her body out into the snow, which is a risky trip, and the smell keeps the hunter close for the rest of the night. Or leave her, and it gets up. Turn her away at the start and none of this happens. You can always tell her to leave when she asks for food.
• Some nights she isn't the stranger (about 1 in 8 of the nights you let her in). The tells: her eyes catch the firelight red; she sits too still and never shivers; she never warns you of anything; and she doesn't ask, she demands ("Feed me."). She eats raw meat and smiles. Feeding her holds her off, but the demands come faster and angrier toward dawn. Refuse her twice and she kills you. Keep her until first light and she stops pretending. The only way out is to tell her to leave.
• The woodcutter (from 11 pm, up to three times a night) mostly sells wood: 1 meat for 7 logs or 2 meat for 15, and at a push 6 logs for 1 cooked meat. On the blizzard night his wood is dry.
• The trader comes some nights, once, from midnight (see below).

That's everyone. Knocks are rare, and nobody but the stranger stays: most knocks late in the night are mimics. Each real person you let in is worth 10 points at dawn.

Familiar voices. The mimic copies whoever you'd open for, word for word, even how they greet you once you've let them in before ("It's me. The woodcutter."). From night 2 it knows the trader's voice too.

Knocks while you're out wait at the door. You can't hear footsteps from the trees, so when you come back the snow tells you: fresh footprints leading up to the door, or none.

Keep the door shut on a real visitor and you hear their footsteps leave. Keep it shut on the mimic and the knocking stops, but no footsteps leave.

The day, and nights 2 to 5

Make it to dawn and you choose: end here and bank your score, or rest through the day and face the next night. A run is up to five nights: the blizzard on nights 3 and 4, and the blood moon on night 5. Longer runs score far more, and the leaderboard marks them with one ☀ per night.

The day is a planning screen over the daylit room. It runs from 6 am to 10 pm: 16 hours, and every choice costs some. Each button shows what time it'll be when you're done.

Action	Hours	What it gives
Chop wood	2	9–12 wood
Hunt in daylight	2	Safe meat, sometimes blood
Check the traps	1	Two catches per trap (from night 2, sometimes fur)
Scavenge the empty village	3	Salt, sometimes blood, sometimes a jar of nails (each board holds through one extra pull). The village tells its own story: barred doors, torn boards, tally marks that stop at two
Repair or board the window	2	Back to three boards. The glass is gone for good, so the wind is in from the start
Bury her	2	Only if you dragged the stranger's body out; it stops drawing the hunter
Sit with the stranger	1	Only if she's alive; she gives you salt and warns you about the floor
Sleep	6	Skip it and the night gets worse; see No sleep below. Sleeping resets the count

The day also thaws every frozen log and spoils any meat that isn't cured. The day screen warns you what the next night brings.

Night 2 keeps what you have and what is broken: resources, traps, the lantern, the boards, the broken window, and the stranger alive, gone or buried. Everything that hunts you behaves as if it were two hours later: the thing in the trees and the knocking start as soon as it's dark, she comes to the window from 11 pm, the walkers from 1 am, the fire burns faster and the mimic knocks more often. The day screen and the start of night 2 both warn you.

New on night 2
Salt	Salt the doorway (2 salt): the next thing you open the door to that isn't a person can't cross; the line breaks instead of you. Salt the sill (2 salt): the next time she would get through the window, she recoils
The thing under the floor	There is a cellar hatch in the room. The floorboards creak and dust puffs up, then the lid lifts and pale fingers curl out, with eyes in the gap. It sits right under the meat rack. Slam the hatch (F/Space). Bar it with a beam (4 wood): slam it in time and the beam stays whole; miss, and the beam breaks instead of it getting out. With no beam, a long pale arm comes up the wall and strips half your meat off the rack, then stays down a long while. No meat, and it takes the stranger: one sharp breath and she's gone. No stranger, and it takes you. While you're out, nobody is there to slam it
Fur	From night 2, traps now and then catch a pelt. Fur makes a coat or insulation, or keep it: 3 points each at dawn

Night 4: the goblins. The blizzard again, and now they come in, two ways.

• At your heels when you come back from a trip (about 1 in 10), and through the woodshed cabinet: they nest among the logs, and the fuller the shed, the more often one tries it. Salt the doorway or the cabinet (one use each), or nail a plank over the cabinet (3 wood): nothing gets through it, but you can't get at your wood either until you take it off.
• From 2 to 3 am the storm drops dead. The window clears, you can see the treeline again, and the goblins come twice as often.
• Each one snatches something the moment it's in and hides in a dark corner (several can share one). Every so often one goes for the rack: up one side, a slip, across, and up the other. Swat it (the button under the rack, or F) before it gets there and it bolts out the door.
• Light its corner and it moves. With nowhere dark left it pinches a torch out, and the wind through a bare window blows torches out too; relighting is free.
• Three inside at once, or the fire dying with one in a corner, and they come for you.

Night 5: the blood moon. The snow stops and the moon comes up red. Every one of them comes, from every part of the woods, to the last fire still burning, and they're all awake from 10 pm. There's no cold and no frozen wood: it's the siege.

• Mimics stand on two feet. The lantern can't tell anymore. Build a slot in the door (6 wood) and slide it open at a knock to see the face. A real person looks right; a mimic is almost right. Sometimes fingers come through the slot and snatch something.
• The blood hour, 3 to 4 am. The moon goes dark, the room floods red, the torches die and won't relight, and the knocks come one after another in voices you trust. Open the door, or even the slot, and the thing in the trees reaches through.
• The swarm, 5 to 6 am. At 4:30 you're warned, and every way in that's still open glows red. From five, any open entrance pours goblins at you: the door opening for any reason, a bare window, an unplanked woodshed cabinet, a hatch without its beam. Her tearing the boards off counts.
• If the stranger died earlier, she comes back to the door with her own voice. Through the slot there's nothing in the hood but a red glow.

The stranger, and the endings. She is not a person. She was the fire of the village, and when its fire went out the things took it. She reached your door two days later, a dying ember. She can only take what fire has touched (cooked meat), raw meat poisons her, and when she starves what's left under the cloak is the dark of a dead fire. Feeding her makes her stronger; your fire going out with her inside weakens her. On the blood moon every one of them gathers at your cabin, and at the fifth dawn:

Ending	How
The Burning	She's with you and strong. She lets the cloak fall, and she is fire. She walks out, and the forest burns with every one of them in it. The winter is over
The Last Ember	She's with you but weak. She has only enough to burn the clearing, and burns herself out getting you through
The Ash	She died along the way, and came back to your door all night
The Cold Hearth	She isn't with you: never let in, sent away, taken by the hatch, or the false one. The sun comes up and nothing changes. The snow begins again
The Keeper (secret)	Your fire never once went out, all five nights, and she's beside you at the end

The endings are simple cards for now; their scenes come later.

The woodcutter's axe. He'll sell his spare for 3 meat, once. Every wood trip then brings back 5–7 logs instead of 3–5.

No sleep. Each day in a row you skip sleep makes the next night worse:

Days awake	What happens
1	Your eyes close every 15–20 seconds or so for 2–3 seconds, and while they're shut you can't do anything: not even burn her back or slam the hatch. Slower hands and trips, and you get hungry faster
2	Longer, more frequent dozes, and things that aren't there: knocks with footsteps but nothing under the door (the lantern shows no feet at all); howls with no eyes in the treeline; whispering at the edge of hearing; her at the window when she isn't (look closely: a faint double of her drifts around her); the hatch rattling three times as often, only one in three real. And every mimic seems to walk up, so footsteps tell you nothing
3	Longer and more frequent still, trips take two seconds more, it howls every few seconds, its eyes and grin flicker in the treeline, and the false hers have no tell at all
4	You don't make it to the first hour

Night 3 is the blizzard. Everything still comes two hours early, and:

The house gets cold	Only a fire burning or roaring keeps the house warm: at flickering it's chilly, at smoldering it's freezing, and you slowly take on the house's cold. A broken window lets the wind in (less through boards, none through shut curtains), insulation helps, and every time the door opens the cold rushes in. You can see it: frost glazing in from the corners, snow drifting in under the window, your breath. Your own cold is in the top left
You can barely see out	The window is a white-out. On normal and hard, if the thing in the trees is close, its eyes show for a moment once every three seconds, very faintly. On insane, never. Listen for its howl, and for the falling howl when it leaves
Trips take half again as long	Wood runs, building the shed, everything outside, and now and then you lose the path for a moment in the white
Frozen logs	Everything you bring in is frozen, even from the woodshed (the woodcutter's isn't). Frozen logs show dark and rimed on top of the pile ("18/25 · 6 frozen") and thaw in about a minute by a good fire; the drying rack thaws them three times faster. Stoking uses thawed wood first; a frozen log burns half as long and hisses
She is quicker in the cold	Her pull on a board is about 30% faster
Fur	Clothes slow how fast you get cold, and the set makes you all but immune: coat (6 fur, 35%), trousers (5, 20%), hat (4, 20%), socks (3, 15%). Fur curtains (5 fur) over the window: click the window to open or shut them. Shut, the wind stays out and the house is far warmer, but you can't see the treeline at all, she is only a faint outline, there's no warning to burn her, and she has less time before she gets a board. Fur is also 3 points each at dawn, so every piece you wear costs you score

Difficulty and scares

Pick a difficulty for each run; each has its own leaderboard.

Normal	The night as it was meant to be
Hard	A little less wood (90% on trips, 85% chopping), 30% fewer catches, hungrier, meat goes bad sooner, a smaller woodshed (70). The grin takes three seconds; she and the hatch are quicker; more of the knocks are mimics. The trader sells one bundle of smoked meat a visit (1 blood + 2 logs for 2 cooked meat)
Insane	The traps barely feed you (42% of normal catches), much hungrier, less wood, a 50-log woodshed that loses some logs to damp each day. The trader comes every night (from 11 pm), charges a jar of blood less, sells an iron trap that never wears out, and trades smoked meat for logs (2 logs for 2 cooked meat, three times a visit). A night with no one knocking is nearly always the last

Challenges go on top of any difficulty, one per run, picked beside the difficulty when you start (challenges.js). Each multiplies every night's score and has its own achievement for surviving all five nights under it:

No axe	the woodcutter keeps his axe	×1.15
No woodshed	the pile by the fire is all the wood you have	×1.3
No lantern	you can never count the feet under the door	×1.2
One trap	never more than one	×1.35
No torches	the goblins have every corner	×1.15
No visitors	the door never opens to a knock: no woodcutter, no trader, no stranger	×1.4

Under each challenge is its record for the difficulty you're pointing at: the best finished run by a person (kept on this computer until there are accounts), otherwise the best finished run by the evolved bots (sim.certifyChallenges), otherwise presumed impossible: no bot survived all five nights in hundreds of tries. Presumed-impossible challenges can still be played.

Bot records (2026-10-22; each a replayable seed and genome in tools/challenge-records.json; 640 to 3,500 runs tried per cell):

	No axe	No woodshed	No lantern	One trap	No torches	No visitors
Normal	5,399	5,514	6,267	3,385	5,605	3,222
Hard	3,991	3,825	4,819	presumed impossible	4,317	presumed impossible
Insane	3,403	3,759	4,107	presumed impossible	3,724	presumed impossible

The bots first called no visitors impossible on normal, and a person beat night one easily: the bot was spending 86 of the 125 logs it gathered in a night rebuilding worn-out traps, and lighting a lantern it had no use for. New genes (trapMax, trapFood, shedEarly, skipSleep) let it hold back on traps and put the woodshed up on night one; it then finished once in about 80 tries. The bots are good at the ordinary game and still weaker than a careful person on the lean challenges, so treat "presumed impossible" as "no bot has managed it", not proof.

Scares (on the title screen) is separate from difficulty:

• Eerie keeps the dread and no jump scares.
• Terrifying adds:
  • a grinding, rising screech whenever something is about to kill you;
  • a lunge at the moment it does: its face, much too close, for a third of a second;
  • when you only just make it back with the grin nearly full, its face filling the window as the door shuts.

Building

Everything you build costs something you could have kept. Build in the room itself: a small amber ember glows over each spot where you could build something right now:

• the window: boards, salt the sill;
• the door: salt the doorway;
• the traps by the door: another trap, or salt one;
• the lantern hook;
• the hatch;
• beside the fire: the drying rack;
• the meat rack: cure;
• the right wall: the woodshed;
• the bedroll: the fur coat;
• the walls: insulation;
• each corner: a torch.

Click an ember for a card with what it does and what it costs. The build button (B) still lists everything.

Build	Cost	What it does
Window boards	8 wood	Three boards. Without them, her first visit at 1 am kills you. Repair one for 3 wood
Trap (up to 3)	6 wood each	The only way to get meat at night (there's no hunting after dark). Raw meat and blood, collected on every trip. Each wears out after a few catches, and sometimes something tears one apart: a heavy iron clank and the chain dragging, and you bring the mangled bear trap back inside the door. The smell keeps the thing in the trees close for longer
Blood lantern	8 wood + 4 blood	Red light under the door shows whether anything is actually standing there. That's the only way to catch the walkers after 3 am. It burns a jar of blood every minute, and goes dark when you run out
Woodshed	25 logs, 1 s outside each	A shed against the outside wall that holds 100 more logs. You build it a bit at a time: each trip carries out the wood you have and builds it in log by log, and you can run back any time without losing what's built. That's also how you spend a pile that's getting too tall. Once it stands, a small cabinet appears in the right wall with a candle beside it: it opens straight onto the shed. Click it to look in. Wood moves on its own: extra logs go into the shed, the pile restocks from it a few logs at a time when it runs low, and the cabinet swings open while they do. The wood count shows what's in the shed
Corner torches (up to 4)	2 wood each	An iron sconce in each corner of the room, where the eyes like to sit. Once you have a woodshed, its candle lights the back-right corner and that torch isn't offered (build it first and you keep both). Burns all night with a faint warm glow, and nothing opens its eyes inside it. The first time you light a corner, now and then a rat bolts out of the shadows
Cure meat	1 salt	Rubs salt into 2 cooked meat so it never goes bad
Drying rack	12 wood	Beside the fire. Thaws frozen logs three times faster, eight at a time. (It no longer smokes meat; salt-cure it instead)
Fur clothes	coat 6, trousers 5, hat 4, socks 3 fur	Each slows how fast you get cold; the whole set makes you all but immune
Fur curtains	5 fur	Over the window; click the window to open or shut them (see night 3)
Insulate the walls	6 fur

The trader

Some nights (about 3 in 5), once, from midnight: slow footsteps and a clink, and a tall man in a long gray coat and a wide hat. Let him in and he opens the coat. His goods hang on hooks in the lining, more than should fit.

Item	Price	What it does
Iron fire grate	3 blood + 1 cooked meat	The fire burns down 40% slower
Snowshoes	2 blood + 2 cooked meat	Every trip is 30% faster
Bone spear	3 blood	If the thing in the trees catches you, you drive the spear into it. It drags itself off into the trees, and you finish your trip in a hurry. Once
Salt	1 blood	3 salt, for curing meat (and salt lines on night 2)
Iron stove (from night 2)	5 blood + 2 cooked meat	Your fire in an iron box with a pipe through the roof. Cooks in 4 s instead of 6, warms you 30% more and burns 25% longer, but throws less light, so the eyes come closer sooner. Replaces the grate
Bone charm	3 blood + 2 cooked meat	For the rest of the night the grin takes seven seconds instead of four: enough to finish a normal wood trip after it gets close, not a blizzard trip. It crumbles at dawn

Score

Only a night survived to dawn scores: for making it, how you lived through it, and what you held on to, which counts for a lot. A well-stocked cabin (say 25 logs, 15 cured meat, 15 blood and a woodshed) is worth 200, twice the dawn itself. On the score screen, what you held on to opens into each thing you kept and what it was worth.

At dawn	Points
Made it to dawn	100
Each real person you let in	10
Each time you burned her back	5
The stranger still with you	25
What you held on to	1 per log (pile and shed), 1 per raw meat, 3 per cooked meat, 5 per cured or smoked meat, 4 per blood, 2 per salt, 3 per fur, 5 per level of fire, and 40 for a woodshed. After a blizzard night, ×1.25
Each dawn after the first	+100, on top of the nights before

The resource bar uses small pixel icons: a log end (with the pile's 25-log limit), then the meat in three counts, cured (dark and salt-flecked, which never goes bad; shown once you have some), cooked (which goes bad in a few minutes and over the day) and raw, then salt and a vial of blood. Hover an icon for its name. The room shows what you're keeping too: elk haunches hang from a meat rack (raw dark red and marbled, cooked seared brown, cured dark and salt-flecked, gray-green when about to turn), and below it a shelf holds corked vials of blood and a crock of salt.

The edges of the screen tell you how close you are: a sickly green when you're starving, and red only when something is about to kill you. Red means the grin nearly full, the dark almost in, her climbing in with fewer than ten logs to take, the hatch opening with no beam, no salt and nothing left but you, a blaze with no blood to douse it, the cold or hunger almost there. Losing boards or food doesn't count.

Every death has its own few seconds before the red screen:

Killed by	What you see
The dark	The last coal goes out. Eyes open one pair at a time all around the room. They blink together, and every time they open again they are closer, until one pair is right in front of you
Hunger	You slump sideways to the floor. Your vision blurs and narrows with each slower heartbeat, and a pair of red eyes waits at the edge of the light
The fire	Flames race out from the pit along the floor and climb the walls, smoke rolls down from the roof, and a burning beam comes down
The mimic	The door bangs open on what looks like a person. It unfolds, too tall for the doorway, its head bending down under the lintel on a broken neck and a mouth splitting down its face. Then it comes in, arms spread
Her, at the window	She pulls herself through the window, drops off the wall and comes across the floor toward you on her long arms
The thing in the trees	Its grin opens all the way and its eyes go red. A scream outside, something dragged past the window through the snow leaving a red smear, and then the door swings open in the wind and the fire sinks. Nobody comes home
The stranger, risen	Her body gets up in jerks, sitting, then standing, then taller than she was, and walks toward you
The thing under the floor	The hatch is thrown open, pale arms come up out of it and across the floor, and you're pulled down into the hole
The false stranger	In the dawn light her shadow climbs the wall, far too tall, red-eyed, its arms spreading across the ceiling, and bends down over you as the light goes out
The cold	A white glaze creeps in from the edges and frost ferns grow over it, your breath shows slower and fainter each time, and the fire seems to shrink away
The white (very rare)	About one blizzard night in a hundred, you lose the path for good. The whiteout swallows the room and a small dark figure walks away into it

Every ending, death or dawn, shows a recap of your night: people let in, mimics kept out, times you burned her back, trips, meat cooked, how hungry you got and your closest call: the nearest you came to any of the threats you survived, such as the grin 92% full, burning her back with 0.4 s to spare, the dark 88% of the way in, slamming the hatch at the last moment or putting out the blaze with a second left. Whatever actually killed you doesn't count as a close call. It also shows an all-time tally, for example "14 nights · 2 dawns · killed by: the mimic 6, her, at the window 3, hunger 2". The tally also appears under best nights on the title screen. The simulation's automated nights don't count toward it.

The top-10 board takes three arcade initials. It's stored in the browser on that computer, like a single arcade cabinet; a shared online board would need a server, which was left out of scope.

Difficulty, tuned by simulation

tools/sim.js plays full nights at high speed through the game's test hook. Its players only use what a person could perceive: the footsteps, the lantern, the howl, the eyes in the treeline.

• Beginner: keeps the fire up and eats when hungry, but opens most doors, ignores the howling, reacts to the claws half the time, rarely builds and feeds the stranger whenever she asks.
• Learner: plays like a beginner, but follows each of the stranger's hints once it has heard it. This models a first-time player who reads.
• Strong: knows every tell. It boards up before 1 am, gets the lantern before the walkers, waits out the howling, burns the claws and feeds the stranger only on her last plea. It reacts a beat late, like a person, and misreads the footsteps now and then.
• Skilled: the same, but with instant, perfect reactions.

Results on 2026-10-17, after hunting was taken out (traps are the only meat at night; they cost 6 wood and catch less):

Player	Nights	Survives	Main causes of death
Beginner	100	0%	the trees 63%, mimic 17%, hunger 8%
Learner	100	13%	hunger 51%, mimic 24%, her at the window 8%
Strong	100	96%	her at the window 3%
Hoarder	100	74%	mimic 20%, her at the window 6%

The hoarder plays like the strong player but with the rush-traps-then-hoard plan: three traps at once, wood until midnight, then as few trips as possible. Before this round that plan let a good player coast through the rest of the night. It still survives less often than steady play (74% against 96%) and scores about the same: the pile caps at 25, meat spoils, traps wear out and hunger keeps you going out.

Night 2, among the runs that reach it (sim.runTwo):

Player	Reached night 2	Survives night 2	Main causes of death
Learner	45 of 200	9%	mimic 47%, the hatch while away 13% (measured before the economy round)
Strong	48 of 60	63%	the hatch while away 15%, the dark 10%, her at the window 10%

Two-night scores for the strong player now land between about 550 and 850. (Keeping a mimic out no longer scores, since letting one in kills you.)

A real first-time player lands between the beginner and the learner, so the large majority of first nights end in death. The doubled lantern cost is what brought the strong player down from about 93% to 84%: it now has to work to have the lantern lit when the walkers start.

The bots need some human sense to be realistic. Beginners sometimes run from a widening grin, and readers cook their meat after the first bout of sickness.

Tuning changes along the way:

• replaced the random death roll in the trees with the visible grin;
• added a grace period after a howl;
• made door visits more frequent;
• tightened wood and hunger;
• made the lantern burn blood every 60 seconds and doubled its cost;
• trimmed trap yields;
• had 60% of late mimics fake footsteps.

The perfect player, evolved (2026-10-19)

perfect in tools/sim.js plays whole five-night runs, days included, and knows every defense from nights 3 to 5 (fur clothes and curtains, torches, salting and planking against the goblins, the slot, the blood hour and the flood). Every choice it makes is a number in a genome (GENES: how bold its trips are, its log reserves, when it eats, trades and buys, how it spends the day).

• Replayable. Every random roll in a run comes from one seeded generator and the game steps in fixed time, so a genome and a seed always play out exactly the same: sim.replay(genome, seed, diff).
• Evolvable. sim.evolve(diff) keeps the best genomes, mutates them, and tests each generation on fresh seeds; sim.pickBest(evo) checks the leaders on validation seeds so a lucky one can't win.
• Saved. The best genomes and their best runs are in tools/genomes.json; sim.replayBest('hard', 0) replays one.
• Balance experiments. sim.sweep(diff, genome, [{ traps: 0.45 }, ...]) measures difficulty variants on the same seeds; sim.measure reports survival per night, scores, causes of death, and night-1 survival with and without a woodcutter or trader knocking.

Hard and insane were rebalanced against the evolved players. Results with the best genome for each, 100 to 150 seeded runs:

	Survive night 1	Reach dawn 1 / 2 / 3 / 4 / 5	Night 1: no visitor / a visitor	Final score (median)
Normal	91%	91 / 86 / 79 / 77 / 75%	9 of 9 / 82 of 91	3,898
Hard	77%	77 / 64 / 51 / 43 / 31%	15 of 20 / 62 of 80	3,212
Insane	51%	51 / 41 / 11 / 6 / 2%	8 of 40 / 69 of 110	2,772

Before the rebalance the evolved hard player finished 13% of runs and the insane one never got past night 2. The playtest kits (DEV_KITS in main.js) are the best genomes' median holdings at each dawn and after each day (sim.kitsFrom).

To rerun the simulation, open the game locally and run this in the browser console:

const sim = await import('/tools/sim.js');
sim.report(120);                                        // night 1, the five older players
sim.measure((await sim.genomes()).genomes.hard, 'hard', 100);   // whole runs, the evolved player

How it's built

Plain HTML, CSS and JavaScript modules, with no framework, no build step and no dependencies.

• Two-layer rendering.

  • The room is drawn at 320×180 and scaled by a whole number, so pixels stay crisp squares.
  • A full-resolution light layer draws the darkness. It cuts soft holes for the fire, the blood lantern, the open door and dawn.
  • The eyes, her claws, the hunter's eyes and the red under the door are drawn on that layer, so they glow out of real darkness.

• The night is one state object advanced in fixed 50 ms steps. Each system is a small update function, gated by the hour:

  • the fire, hunger, spoilage and dread;
  • the hunter's cycle and trips;
  • the stranger's hunger and hints;
  • cooking and sickness;
  • the blood lantern's fuel;
  • her phases at the window (idle, warn, crawl or reach, then steal or retreat);
  • door scheduling.

  Dialogues pause the night, and the flames, snow and flicker drop to half speed so the pause is visible.

• Her is drawn at half-pixel detail on the light layer: black, with a dark-red rim, backlit by a red glow that also lifts the darkness enough to show the boards she's clawing at.

• Sound is generated with the Web Audio API, with no audio files:

  • fire crackle;
  • wind;
  • knocks and footsteps in snow;
  • the howl;
  • a board splintering;
  • the hiss of the burning branch;
  • glass shattering, and the rhythm of thuds as she works at the boards;
  • teeth chattering, retching, and meat sizzling on the fire;
  • a scream outside;
  • the heartbeat;
  • a death drone and a dawn chord.

• Scoring and the leaderboard are pure functions in score.js, with Node unit tests. Stored entries are sanitized before use.

index.html          markup: canvases, HUD, actions, dialogue, panels, title and ending screens
style.css           pixel-styled UI, all sized from one --s scale variable
main.js             the night, threats, trips, doors, drawing, UI wiring
sound.js            procedural audio
score.js            scoring and leaderboard logic (pure, tested)
tests/              Node test runner tests
tools/sim.js        difficulty simulation, the evolved perfect player (not deployed)
tools/genomes.json  its best genomes and replayable best runs
tools/challenge-records.json  the bots' challenge records, replayable
challenges.js       the challenges, their multipliers and the bots' records
docs/               README screenshots

Phones

The game runs in a phone browser, held sideways.

• Fit: the scene scales to fit the screen: whole-number scales when there's room, a fractional scale on small phones. It respects notches.
• Touch: on touch screens the buttons grow to about 40 px tall, the keyboard hints are hidden, and double-tap zoom and long-press menus are disabled.
• Upright: held upright, it shows a turn-sideways screen and the night waits.
• Sound unlocks on the first tap.
• Fullscreen: the button is hidden where the browser can't do it (iPhone Safari).
• Performance: the light layer is capped at 2× pixel density so the glow stays smooth on high-density screens.

Run locally

python -m http.server 5350 --bind 127.0.0.1

Then open http://127.0.0.1:5350.

npm test

Pushes to main deploy to Vercel automatically.

Verification

As of 2026-10-22 (v0.72):

• 18 unit tests (npm test): scoring and the leaderboard, the achievement store, and the challenges (multipliers, their achievements, records, board entries).
• Simulation: thousands of seeded full runs across every difficulty and challenge (tools/sim.js). Runs are deterministic: a saved seed and bot genome replay to the exact same score, checked after page reloads and with other runs in between.
• Random-input stress runs on every night and difficulty (random builds, choices and timing), checked for script errors and broken state (NaN or negative counts). None found.
• Every death and jump scare reviewed frame by frame in the death lab, and every playtest start and challenge rule checked in the browser.
• Played by people: Zach and his sister have played every version on desktop, including a full Normal run to the Keeper ending (3,765 points), Insane nights, and a no-visitors run, plus the sound and the scare settings.
• Never tested: a physical phone or tablet (only the browser's phone emulation), a Chromebook, Safari, or players outside the family. Screenshots in docs/ are staged with the test hook, so their numbers aren't from real play.

Music

The background music is generated in the browser like the rest of the sound: a low, slowly breathing drone under a warped music box picking out a minor-key lullaby one note at a time, never quite in tune. As the night goes on, and as the dark closes in, a sour note creeps into the drone and the music box plays faster, with notes that clash. It's quieter during the day, and silent at dawn and when you die. N or the music button turns it off (remembered per browser).

Experimental features

Scroll to the very bottom of the achievements and there's a faint "experimental features" switch, off by default. With it on, a few silly, deliberately unbalanced extras can be found in the game; how to set them off is left for players to discover. One lasts only for the game it's found in, and a night that uses one counts as a playtest night: no stats, no leaderboard, no achievements.

Third-party material (not ours). One of these extras is a DOOM tribute and uses two things that belong to others, in a small non-commercial fan project shared with friends. We'll remove either at once if the owners ask:

• Music: music/rip-and-tear.mp3, a close variant of "Rip & Tear" by Mick Gordon, from the DOOM (2016) soundtrack, © id Software / Bethesda.
• Shotgun art: assets/doom-shotgun.webp, the super shotgun cut out of a DOOM Eternal screenshot and colour-graded, © id Software / Bethesda.

The gore, bullet puffs, muzzle flash, shot and reload sounds are original, made in code.

Achievements

54 achievements, under achievements on the title screen, with a toast and a chime when you earn one:

• A death for every way to die, 19 in all, including the very rare death lost in the white. A few are secret, shown as ??? with a hint until you find them.
• Surviving each of the five nights, and finishing on hard and on insane.
• The five endings.
• The six challenges, one for surviving all five nights under each.
• Feats. A few that mean something:
  • keeping her alive to the third dawn;
  • seeing through the false stranger;
  • counting the feet under the lantern;
  • turning away a walker;
  • burning her back with less than half a second to spare, or five times in a night;
  • dousing a blaze;
  • the bone spear;
  • filling the woodshed to all 100 logs;
  • holding 200 points' worth at one dawn;
  • a 1,000-point run.

They're stored in this browser for now (achievements.js). Each unlock keeps its time and a "not synced yet" flag, so a future account system can upload what you earned before you signed in. Simulated and playtest runs don't earn them.

Playtesting

Open the game once with ?dev on the address (https://firelight-topaz.vercel.app/?dev) and the title menu gets a playtest button, remembered in that browser. Pick a difficulty, then start at the day before a night or straight into night 2, 3 or 4 (optionally a few days awake), with the kit a strong player typically has by then on that difficulty (the evolved bots' median holdings: wood, meat, blood, salt, fur, traps, and what's built). Playtest runs don't count toward the stats or the leaderboard.

The playtest menu also opens the death lab (or go straight there with ?lab, https://firelight-topaz.vercel.app/?lab): every death on its own in an empty lit cabin, set up the way the room looks when it really happens (night 4's goblins, night 5's blood hour, out in the trees for the hunter and the whiteout), plus the flood from each way in, the goblins from one, two or three corners, the jump scare for every death, the face at the window on a close call, and the mimic stopped at the salt line. Play, pause, restart, scrub, slow it to 0.25x or 0.5x, switch scares between eerie and terrifying, and turn sound on or off (space, R, the arrow keys for one frame, Esc to leave). Scenes run from a fixed seed, so scrubbing shows the same frames each time. Nothing in the lab touches your saved night, the stats, the leaderboard or achievements.

The version is in the bottom-right corner (v0.78 is the 78th commit; the number counts every commit, docs included), so you can tell a refresh picked up the latest build.

Future ideas

Noted for later and very much subject to change:

• Accounts and a backend (Render + MongoDB), so scores, challenge records, achievements and stats are shared between players and devices.
• Stacking challenges.
• Custom ending animations, sounds and sprites.
• The day overhaul: a village worth exploring.

Known limits

• Untested hardware: never tested on a Chromebook, Safari, or a physical touch device.
• Everything is per-browser: the leaderboard, challenge records, achievements and stats live in local storage until there's a backend.
• The bots are weaker than a careful person on the lean challenges. "Presumed impossible" means no bot managed it in thousands of tries, not that it can't be done: a person beat night one of no visitors easily while the bots were still failing it.
• The simulated players are approximations. Real players may find a threat harder or easier than the numbers suggest, especially the footsteps tell, which is text plus a sound.
• Phones are landscape only: held upright, the game shows a "turn your phone sideways" screen and pauses. Checked in the browser's phone emulation at 375×812 upright and at 812×375 and 568×320 sideways, not on a physical phone.
• School web filters may block vercel.app.

Credits and AI assistance

Inspired by A Dark Room by Michael Townsend / Doublespeak Games. No code, text or art was copied from it.

The hidden DOOM tribute uses "Rip & Tear" (Mick Gordon, DOOM 2016) and DOOM Eternal's super shotgun, both © id Software / Bethesda, credited under Experimental features. They aren't covered by this project's rights and will be taken down on request. The game also credits them on screen when the tribute starts.

Built with heavy AI assistance (Claude Code) under Zach Shirley's direction:

• Zach:

  • Concept and look: chose the concept and the chunky pixel style with smooth firelight.

  • Core horror elements: the eyes in the dark, and visitors with dialogue.

  • This redesign: called out that the previous version had no stakes, and set:

    • the target that most players should die;
    • one short night that escalates;
    • wood-stockpile scoring;
    • the hand at the window that breaks boards and steals wood;
    • the blood lantern as an easier tell;
    • doors that never open by themselves;
    • a hunger mechanic and dangerous hunting trips;
    • no jump scares.

  • The follow-up round:

    • a stranger mimic indistinguishable except by knowing there's only one;
    • the stranger's hunger, the third plea, and the consequence of letting her starve;
    • her redesign as a black, red-glowing claw that shatters the glass and crawls in through a bare window, with the board-breaking rhythm;
    • more frequent, more dangerous doors, so the blood lantern and traps earn their place.

  • The polish round:

    • muting on the title screen and in background tabs;
    • a real hunger warning;
    • a costlier lantern and weaker traps;
    • raw and cooked meat with sickness, and icons;
    • the glass always breaking first;
    • the grin;
    • points for letting the right people in;
    • an eat cooldown;
    • a visible pause;
    • visitors waiting while you're out.

  • The next round:

    • cold instead of hunger, after Zach's mom pointed out nobody starves in one night;
    • the night recap and the all-time death tally;
    • the false stranger, who demands to be fed and kills you at dawn;
    • the grin tied to the creature's eyes instead of floating free.

  • Day 2:

    • the day screen and its choices;
    • salt;
    • nails;
    • tiredness;
    • the thing under the floor;
    • night 2's two-hour head start;
    • two-night scoring.

    Zach asked for a second day and left the design to Claude; the outline came from an earlier recommendation he had approved in principle.

The font is VT323 (SIL Open Font License).

License

All rights reserved; source is public to read. No open-source license has been chosen yet.