How to run it

1. The desert takes its turn on the day

Not on a round. On the day. Roll the d100 twice per day of travel: once in the morning while everyone is still making decisions, and once in the late afternoon when they are tired and want to stop. On genuinely bad country, roll a third time in the dead middle of the day, when the sun is doing the work.

Twice is the right number. It is enough that the land is present every single day, and few enough that the day does not turn into a list of events. If a roll hands you something the party is already dealing with, roll again or take the row you want. This is a tool, not a slot machine.

It hits everybody. The desert does not take sides, and a table notices fast if it only ever lands on the players. One exception: people born out here solved the glare and the sun angle before they could walk, so rows 41 and 45 skip them. The party squints. The woman who lives here does not.

2. Almost none of it is damage, on purpose

Read down the table. Two rows out of a hundred deal a point or two. Everything else takes water, time, distance, gear or morale.

A desert that deals 4 damage an hour is a bad monster with no stat block. It reads as weather in a video game and it gets treated like weather in a video game. A desert that costs them a full skin, half a day and the only boots that fit is a place they will talk about having crossed.

Those are the five currencies. Water first, because everything else can be bought with it. Then time, then distance, then gear, then morale. When you improvise off a row, pick one of the five and spend it.

3. Tell them it is coming

The dust wall is visible for an hour before it arrives. The afternoon wind comes at the hour it came yesterday. The shade is obviously going to move, because the sun is obviously moving. Say so.

Announced pressure makes players plan. Unannounced pressure makes them fatalistic, and a fatalistic table stops trying things, which is the exact thing you were trying to fix.

About the heat clock

Seven rows below say the heat "ticks." Use whatever your table already uses for that.

If you use nothing, use this: mark a box for every hour a character spends in the open with the sun up. On the fourth box, one level of exhaustion. The boxes clear on a long rest taken in shade with water to spare.

The rulebook has its own numbers for thirst and they are stricter than mine. Use those if your table wants the survival game played straight. This version exists so the clock is one line you can hold in your head while you are also running everything else.

d100: What the desert does on its turn

Ten bands of ten. Find the band, read the row. The first half is the sky and the ground and the water. The second half is everything out here that is alive, or was.

Roll	The band	What it covers
1-10	The weather turns	The day is not the day they packed for
11-20	The heat	What it does to metal, to animals and to the clock
21-30	The wind and what it takes	Whatever it can lift off you and carry away
31-40	Water	Finding it, losing it, and what a skin is worth
41-50	The light and the distance	Glare and shade and distances you cannot judge
51-60	The small lives	The things underfoot and in your clothing
61-70	Something noticed	What follows and circles and waits
71-80	People	Everyone else who is out here doing this
81-90	What the desert kept	Ruins and bones and old roads
91-100	The day itself	Whole days, and some of them are good ones

Roll the desert's turn

The Weather Turns

d100	What happens
1	Unusually hot, even for out here. Not a heatwave anybody has a name for. Just a day ten degrees past what they packed for. Every heat tick lands an hour early. The animals know before anyone says it.
2	The afternoon wind arrives, on time. It came at this hour yesterday and it will come at this hour tomorrow. Anyone who has crossed this country before is already looking for a rock to sit behind. Anyone who has not will spend ten minutes not understanding why.
3	The cold comes early. The temperature falls off a cliff two hours before dark, while they are still walking. Anybody who stripped down for the afternoon is carrying wet clothes into a cold night. The halt gets called earlier than planned and it costs them the last good hour of light.
4	One cloud. A single cloud, and its shadow is crossing the ground at about walking pace. Anyone inside it is out of the sun for exactly as long as they keep pace. It is free, it is temporary, and it does not wait.
5	It rains. Ten minutes of real rain, hard enough to sting. Every open container fills. Every dry wash starts to move. The ground goes from dust to grease and back to dust inside the hour, and every plant within sight opens like it has been waiting years, because it has.
6	It rained somewhere else. The wash they are walking in, because a wash is the easy walking, starts to run. They have somewhere between one minute and five to get up a bank. Nothing here is trying to kill them. The water does not need to try.
7	Dry lightning. A storm with nothing under it, walking along the ridge line. Not a drop reaches the ground. Something out there catches, and by evening there is smoke on the horizon in a direction that matters to them.
8	The haze. The sky turns the colour of skimmed milk and stays there all day. No sun to steer by. No shadow to tell the hour by. Not one degree cooler either. Anyone navigating by the sun is now navigating by argument.
9	The wall. Dust from edge to edge of the world, visible a full hour before it arrives. They have that hour. What they do with it is the whole row: dig in where they are, run for the high ground, or try to beat it to the rocks and find out they could not.
10	Dew. Last night's cold was worth something. A cloak left out flat holds a swallow of water at first light, and so does any smooth stone that spent the night in shade. Not much, and free. It is gone twenty minutes after the sun clears the horizon.

The Heat

d100	What happens
11	Metal turns on you. Anyone in metal armor, or carrying an unwrapped metal weapon, has disadvantage on their next Constitution saving throw, and the heat ticks for them and for nobody else. A wrapped hilt is one of those small competences that marks out who has done this before.
12	Armor becomes a decision. Anyone in medium or heavy armor takes their next heat tick an hour early. Taking it off costs ten minutes and leaves them walking through open country in their shirt, which is a different kind of exposed.
13	The water is warm and tastes of the skin. It still works. Nobody enjoys it, and the next person to fill up will carry the extra weight without one word of complaint.
14	The sweat stops. On one character, and it is the dangerous sign. If nobody does anything about it, the heat ticks twice for them at the end of this hour.
15	The rock face radiates. The cliff they picked for the noon halt has been in the sun since dawn. The shade is real. The rock behind it is not, and anyone sitting within five feet of it takes their next heat tick early.
16	Wax, glue and pitch fail. Sealed things unseal. A fletching. A hilt wrap. A stoppered flask. A sealed letter. One of them, and it should be the one that matters.
17	The grip slips. Hands go wet and then dry and then wet again. The next natural 1 anybody rolls with something in their hand means it is on the ground now, and out here that matters most on a slope or over water.
18	The animals suffer first. Any mount or beast is blowing and balking. It obeys one more command, and then it needs water or shade before it obeys another. Everybody sees this happen and everybody does the arithmetic about themselves.
19	Noon. For one hour, everything with sense is lying still in shade. Anyone travelling through this takes two heat ticks instead of one, and anyone hunting them is not hunting them right now.
20	The heat ticks for everybody. No save. No exception. No clever answer. The desert is simply hotter than it was an hour ago, and the clock says so.

The Wind And What It Takes

d100	What happens
21	The wind takes the words. Nobody hears anything past thirty feet, and it stays that way for an hour. The shout about the wash does not arrive. Neither does the order to close up. Whatever they agreed before it started is what they are doing.
22	It takes the fire. Any open flame smaller than a bonfire is out. Relighting costs ten minutes and shelter, and there is no shelter. Cold food tonight, and everyone finds out how much they were counting on the one hot thing.
23	It takes the tracks. Every footprint older than a minute is gone, theirs and everything else's. Whatever they were following, they are now guessing about. Whatever was following them has the same problem, which is worth exactly as much comfort as it sounds like.
24	Something light goes. A hat. An unrolled map. A cloak nobody tied down. A focus somebody set on a rock for one second. Pick the thing that will cost the most to lose and put it three hundred feet downwind and still going.
25	It fills what you left open. The pack. The pot. The wound. Any waterskin left unstoppered. Sand in all of it. The waterskin is the one that counts: grit in every mouthful for the rest of the crossing, and no way to strain it out.
26	It takes the smell of you. And hands it to whatever is downwind, which is a direction nobody has been watching, because the wind was going the other way this morning.
27	Sand in the mechanism. Anything with a moving part sticks. A crossbow. A lock. A lantern's shutter. A clockwork thing. One use, one failure, then it works again once somebody gives it a patient minute.
28	The wind changes direction. Everything anybody did to get upwind or downwind of anything is now wrong. Fire, smell and smoke all go the other way, and the camp is built facing the wrong side.
29	You can smell what is upwind. Smoke perhaps. Or an animal. Or rot. Or cooking. Whatever it is, it is closer than they thought, and it is in a direction nobody was watching.
30	The wind is louder than you are. All day. Nobody is sneaking up on anybody, and nobody is being sneaked up on either. It cancels out, and by evening everyone has stopped talking and is oddly alone inside it.

Water

d100	What happens
31	Water, out at the edge of it. It is not water. Any creature that has gone a day without a full skin makes a DC 10 Wisdom saving throw or spends the next twenty minutes walking toward it.
32	A seep. Real water in a crack in the rock, a cupful an hour. Filling everything takes most of the day. Something already knows about this place and comes back to it, and that something has a schedule.
33	A skin fails. One waterskin has been leaking since morning and nobody noticed. It is the fullest one. Say whose it is, then let them handle the rest of it.
34	The skins do not match the tally. Whatever was counted this morning, there is less water now than the arithmetic allows. Nobody has been careless and nothing has leaked. The heat has simply been taking a share nobody costed, and the party is by most of a day.
35	Something comes to drink. A creature you have not introduced yet walks into the halt and goes for the party's waterskins, not the party. If they let it drink, it leaves. If they do not, they learn what it is.
36	The well is salt. A real well, cut stone, obviously old, obviously dug by people who knew what they were doing. It is undrinkable now, and it was not always. Somebody built a life on this and the life is gone.
37	A cache. Buried water under a marker, and the marker is a code: three stones, a scratch, a knot of cloth. Whoever left it will want to know who took it.
38	Blood is wet. Every caravan out here knows it and almost none of them will say it out loud. It buys an hour and costs the next two, and a dead animal is worth less than a slow one.
39	Thirst stops being a number. Dry mouth first, then a headache sitting behind the eyes, then the arithmetic starts looking optional. Describe the symptoms as they arrive and let the table do the arithmetic themselves.
40	It rained here, recently. Green in the low ground, standing water in a hollow, and every living thing for ten miles already knows and is on its way.

The Light And The Distance

d100	What happens
41	Glare off the pan. The salt throws the whole sky back up at you. Anyone without shaded eyes has disadvantage on sight-based Perception until they get out of the open, and they are not getting out of the open today.
42	Heat shimmer. Everything past sixty feet is wobbling. Nobody can tell a person from a post, or four riders from six, until they are close enough that it is too late to have made a plan about it.
43	The horizon lies. The thing they have been walking toward is either much further away or much larger than they assumed. Pick the reading that costs them more, and tell them plainly the moment they find out.
44	The light goes flat. No shadow anywhere, so nothing has depth and nothing has a distance. Whatever the scout says about how far the ridge is will be wrong by half, in the direction that costs more, and nobody finds out until they get there.
45	The sun tips over. The angle drops and the rest of the afternoon is walked into it. Anyone facing that way has their eyes half shut and is not seeing anything on that side of the world until the line of march changes or the sun goes down.
46	Something flashes, far off. Metal perhaps. Or glass. Or water. It happens once. It will not happen again while anybody is watching for it.
47	The shade moves. The rock they picked for the noon halt stops being shade about forty minutes in. Staying in it means getting up and following it around the rock, and by the third move somebody suggests they may as well be walking.
48	First light. For about twenty minutes at dawn the whole day's ground is visible at once. The ridge. The gap. The thing standing out on the flat that will be gone by nine. Whatever they see now is the last honest look they get, because after that the middle distance goes to haze.
49	Dark comes fast. Sunset out here is minutes, not an hour. Whatever they were going to do in daylight, they are doing half of it in the dark.
50	The moon on salt. Bright enough to read by, which means bright enough to be seen by. Nobody hides tonight, and nobody needs a torch either. Night marching is suddenly the sensible option and somebody is going to suggest it.

The Small Lives

d100	What happens
51	The small things come up. Whatever they chose to sit on is somebody's roof, and the somebodies object. Anyone who stays put takes 1 poison damage and spends the next hour finding legs inside their clothing. Moving costs them the halt.
52	Something in the boot. One character, the next time they put a boot on. It is not lethal and it is not funny to them.
53	A snake under the only shade. The shade is real and the snake is not moving. Somebody has to decide, and the snake does not want the fight either.
54	The flies find the wound. Anyone below half their hit points is being actively bothered. Concentration, delicate work and sleep all get harder until the wound is properly covered.
55	A swarm crosses the path. Not hunting. Just going somewhere, in a column six feet wide. Waiting costs ten minutes. Walking through costs 1 poison damage and a great deal of complaining.
56	Ants take the food. Whatever was not sealed is gone or crawling. One day of rations, and the party gets to decide whose.
57	Something venomous and slow. It is right there and it is obvious, and it cannot catch anybody. It is only dangerous to something that is not looking, which out here is most things, most of the time.
58	Every insect stops at once. The noise the party had stopped hearing is suddenly not there. Something bigger has arrived and has not shown itself yet.
59	A burrow collapses. One person's foot goes through into a tunnel a foot wide and two feet deep. Not a trap, not damage. Whatever dug it is a size worth thinking about.
60	Nothing bites. No flies. No ants. Nothing underfoot at all, for a hundred feet in every direction. Living things avoid this patch of ground, and they have a reason.

Something Noticed

d100	What happens
61	Something starts circling. High up and patient, in no hurry at all. It is not a threat. It is an announcement, and everything on the horizon can read it.
62	A fresh track crosses theirs. Big and deep and heading the other way at speed. Whatever made it was not hunting. It was leaving.
63	You are being paralleled. Something has been on the next ridge over for a while, matching pace, never closing. It will keep doing that until they stop.
64	Dust on the horizon that is not weather. Too narrow and too steady, and pointed at them. In about an hour it resolves into either riders or a herd, and the difference matters.
65	Something answered. The noise the party made a minute ago got a reply, from a direction nobody expected. It was not words.
66	The scavengers arrive early. Before anything has died. They know something the party does not, or they know something about the party.
67	A watcher on the ridge. Visible at the edge of sight, gone the moment anybody looks straight at it. It was there. Do not walk it back.
68	The back-trail has a visitor. Something has stepped in their prints since they made them, and it did not try to hide that.
69	They are waiting at the water. Not on the road. Whatever is out here has worked out that everybody has to drink eventually, which is smarter than anything the party has done today.
70	It is herding you. It is not hunting. Every easy line of travel for the last two hours has been the same easy line, and it has been bending, and it is not bending anywhere they chose.

People

d100	What happens
71	A caravan, going the other way. Twenty animals and six people, and no interest in stopping for long. They will trade water for metal at a rate that is robbery and fair at the same time. They also know exactly what is behind them, which is where the party is going.
72	A work gang. Eight people cutting salt or digging or hauling, under one person who is doing none of it and is watching the horizon instead of the work. Ask who owns this. The answer is a whole adventure and you do not have to give it today.
73	Somebody who lives here. One person on foot, carrying about a tenth of what the party is carrying, entirely comfortable. Not a guide. Not for hire. They will answer two questions and then they are gone, so make the party choose which two.
74	A warning, and no explanation. Somebody they pass tells them not to go the way they are going. They do not raise their voice about it and they do not stay to argue. Then they carry on in the direction they were already headed, which is not the direction they just warned about.
75	A cairn that has been rebuilt. Stacked stones, put there deliberately and kept that way. Cairns are built by people and rebuilt by people, and the stones on top of this one are a different colour from the stones at the bottom. Somebody comes out here. Recently.
76	A camp, still warm. Ashes with heat left in them, a windbreak, and the impressions of six people who left in a hurry and left useful things behind. They are less than two hours ahead. The party can catch them, and has to decide first whether that would be a rescue or an ambush.
77	Somebody else's rubbish. A page. A bandage. A broken strap. A child's shoe. None of it walked here, which means people are that way, which means the map is wrong about where people are.
78	The toll. Two people sitting in the only gap in the ridge for eleven miles. They are polite. They are armed the way a farmer is armed and not the way a soldier is. The price is water or metal or a name, and there is no version of this where going around is cheaper.
79	Somebody wants to come with you. They have a reason and it is a good one, and they will slow the party down by about a fifth. They know that. They are asking anyway.
80	They were here first. The shade the party has been walking toward since ten this morning has people in it. Six of them, with animals, and they are not moving. There is room for everybody if everybody is reasonable. It is the only shade for two hours in any direction.

What The Desert Kept

d100	What happens
81	Something surfaces. A wheel. A roof beam. A hand. The wind has taken a foot of sand off a buried building since the last time anyone came this way, and the top of it is out in the open. It will be covered again by next season.
82	A road. Dressed stone under the sand, two carts wide, going somewhere that is not on the map and coming from somewhere that is not either.
83	A body, dried whole. Not a skeleton. Skin and clothes and a face. It could be forty years old or four hundred, and it is still holding something.
84	A wall with a door in it. Twenty feet of masonry and nothing on either side of it. The door is shut. The door has always been shut.
85	A tree. A single tree, alive in the middle of nothing. Which means water. Which means it has been fought over.
86	Coin. A scatter of good metal, half buried, worth exactly nothing out here against a full skin. It was worth something to whoever was carrying it.
87	A word cut into stone. In a hand nobody at the table uses, weathered but deliberate, at about eye height for somebody taller than a person.
88	A boat. Thirty feet of hull with its ribs showing, sitting on open flat ground, two hundred miles from anything that could float it. It was not carried here. It was built here, back when here was somewhere else.
89	Somebody's tools, laid out. A row of them on a flat stone, in the order you would use them, squared up and clean. Whoever set them down meant to be back inside the hour. That was a long time ago.
90	Stairs. Twelve steps of cut stone going down into the ground, and then sand. No building. No door at the top. Digging it out is a day of work, and the party does not have a day, which is the entire point of the row.

The Day Itself

d100	What happens
91	A genuinely good day. Cool enough to move well, no wind worth the name, firm ground from the morning halt to the evening one. They cover a full day's distance and a bit more. Hand it over without a catch. A table that has been paying the desert all week needs to watch the ledger run the other way once.
92	The far side is closer than it looked. Whatever they have been pacing themselves to reach is half a day nearer than the map said. Give it to them. The desert is allowed to be generous.
93	Good ground. A gravel pan as hard as a road, running most of the way they want to go. Add a third to the day's distance. Anyone who has walked one of these knows it will end abruptly and is already looking for where.
94	A gift. Something small and free that the desert did not owe anybody. Dry fuel off a dead tree. A windbreak somebody built and left standing. An overhang deep enough for the whole party. Take the row's word for it and hand it over with no price attached.
95	The night is worth it. Cold and clear and completely silent, with more stars in it than anyone at the table has seen in their own life. Nobody stands a bad watch tonight. Ask each player what their character is thinking about, listen to the answer, then let them sleep.
96	The country runs out of landmarks. No ridge, no rock, no scrub worth naming, for as far ahead as the map covers. Navigation is dead reckoning and the sun until something stands up out of the ground again. Nobody can tell how far they have come except by how much water is gone.
97	The day is long and there is nothing in it. Nine hours of the same ground, no decision in it, nothing to look at. The country does not do one single thing. Tomorrow's rolls come on tired people.
98	Half a day in hand. The country has been kinder than the map promised and the party is ahead of where they meant to be. The next water is still where it was. So is the next dark.
99	The people who live here have stopped. Whoever else is on this road has pulled up two hours before dark and is making camp in the open. They have a reason and it is not weakness. They will say what it is if they are asked.
100	Nothing. No wind. No weather. Nothing on the horizon and nothing underfoot. The desert skips its turn. A week of this country taking two turns a day, and then a day of flat, complete quiet, and out here quiet has never once meant safe.

d20: Why today is worse than usual

Roll once, before they set out. It is the frame the whole day sits in, and it is the one thing on this page the players should be able to work out for themselves by noon.

Roll the day

d20	What happens
1	The wind has been up for three days. Everyone's eyes are raw before anything begins. Sight-based Perception is at disadvantage until they get an hour out of the wind.
2	The water is short. Somebody sold them four skins and filled three. They will find out at the worst hour of the worst day, which is the only way anybody ever finds this out.
3	It rained a month ago. There is green in the low ground. Everything alive out here is therefore also in the low ground, and the low ground is the easy walking.
4	It is the hottest week in nine years. The last three people they passed said so, and none of them stopped to explain.
5	Something died upwind. Roll on the 61 to 70 band twice as often today.
6	A caravan is half a day ahead. Its ruts are the only good footing for miles, and following them means arriving after whatever the caravan already woke.
7	The nights are wrong this month. Cold enough that a watch stood without a fire costs a level of exhaustion, and a fire out here can be seen from a very long way off.
8	The salt is blowing. Every cut stings, every skin tastes wrong, and anything steel wants oiling tonight or it starts to pit by morning.
9	There is a wind that arrives at the same hour every afternoon, and the people who live here plan their whole day around being somewhere else when it does. The party has not met anybody who lives here.
10	The moon is full. The nights are bright and cold, nobody sleeps well, and everything that hunts at night can see as far as they can.
11	There has been no wind for a week. The dust the party raises hangs in the air behind them in a line, pointing at exactly where they are.
12	The guide is guessing. They have not said so and they will not say so. They are one landmark behind and closing the gap by walking everybody faster.
13	Somebody local warned them off this route this morning, in a tone that was not superstition, and did not explain, and did not stay to argue about it.
14	The animals are wrong. No birds since dawn. Nothing on the flats. No tracks less than a day old. The whole area has been vacated by things that knew to leave.
15	Two of the skins are the cheap kind, and the seams are already weeping. They will hold today. They will not hold tomorrow.
16	It is a holy day for people the party has not met, which out here means the wells are attended and the roads are watched.
17	The heat broke overnight and it is the most pleasant day in a month. Roll the day's second condition as well, because a mild day is when people take chances.
18	There is smoke on the horizon in the direction they are going, and it has been there since first light without moving.
19	They are being followed and they already know it. They simply have not said it to each other yet. Let whoever says it out loud first have the moment.
20	Nothing is wrong. Good weather. Full skins. Easy footing. Every local they passed on the road this morning was going the other way.