Dark Sun for Sword of Cepheus: Part I – Desert Survival Rules

I’ve always been intrigued by the Dark Sun setting TSR put out for AD&D back in 1991. It’s got a bleak, weird, post-apocalyptic quality to it. However, I’ve always thought AD&D wasn’t really the right system for it. So I’ve decided to make my own version using The Sword of Cepheus, the Cepheus Engine-based fantasy RPG by Stellagma Publishing. For those of you unfamiliar with the Cepheus Engine, it’s essentially an open-source version of the classic Traveller RPG system.

Part of the charm of the Dark Sun setting is the barren desert setting. It sets the mood, and provides a challenge for the players. The following are rules for desert travel in my Dark Sun conversion. I think they’re a little more brutal than AD&D, which is a plus, in my eyes.

One of the best parts about creating a Traveller/Cepheus setting is that there are over 40 years of material to pull ideas and mechanics from. A lot of the following are inspired by Zozer’s Dirtside supplement and their Hot Zone adventure. Another good source is The Desert Environment by Gamelords, which has incredibly detailed rules for desert survival. It’s a bit more detailed than I needed, but is full of fascinating bits. (I’ll probably steal the rules for arroyo flash floods)

Desert Travel

Traveling across the open desert will cause gradual damage to travelers. It can be lessened with suitable clothing, and plenty of water. The damage can be tracked hourly or daily as convenient. For simplicity’s sake, I’m assuming characters will travel 8 hours a day (with frequent breaks, and sleep periods). 

ClothingHourly DamageDaily Damage
Suitable clothing (light robes, hat)-2-16
Unsuitable clothing-3-24

Survival Roll

If the player makes a Average (6+) Survival roll, they can take 1 less damage per hour / 8 per day.

Rugged Terrain

Traveling across difficult terrain (wading through silt, canyons, foothills) will cause extra damage: -2/hr or -16/day


If the players are traveling with a caravan, it’s safe to assume all of their physical needs are being met, and no damage is taken.

Traveling At Night (optional)

Traveling at night will cause less damage (1 per hour, 8 per day), but the characters will need to find proper shade to sleep in during the day. If they don’t have tents, a Difficult (8+) Survival roll can be used to find shelter. If shade cannot be found, they will only recover desert damage as if they received No Rest (see below)


Drinking water can reduce the damage caused by the desert environment. This will only restore damage from thirst, not any other type of injury. It will not raise stats above their original level. Thri-kreens need considerably less water, while half-giants need more.

Amount of Water per hourNormalThri-KreenHalf-Giant
2 liter+2/hr, 16/day+3, 24/day+2/hr, 16/day
1 liter+2/hr, 16/day+3, 24/day+.05/hr, 4/day
1/2 liter+1/hr, 8/day+3, 24/day+.05/hr, 4/day
1/4 liter+.05/hr, 4/day+2/hr, 16/dayNo gain
0No gainNo gainNo gain

Recovering Damage from the Desert

Resting one day and night in shade: recover 1d6 + End DM
Resting for twelve hours in shade: regain 1D3 + End DM
No Rest: regain 1 point + End DM


A human mercenary (A8A987) is fleeing a caravan overrun by elvish raiders. He was able to grab four 5 liters of water before he fled. He has a 10 hour journey to the next village. That is 1/2 liter of water every hour. Assuming he has suitable desert clothing, he’ll take 20 points of damage from the desert environment. With the water, it will reduce the damage to 10 points. Assuming nothing else happens, he’ll arrive alive, with a bit of heat exhaustion.

Simple Desert Rules

If you don’t want to keep track of any of that, try this: 1D damage per hour in the desert. 2D if they have no water or supplies.

Desert Hazards

Sandstorms: Any player with a Survival skill of 1 or more can warn of a oncoming sandstorm. An Athasian sandstorm will last 1Dx8 hours . Visibility will be only be a few meters. Characters not in shelter will take 1D damage every ten minutes.
Whirlwinds: The Wanderer’s Journal mentions the following (pg 2):
Columns of superheated air can rush upward in terrific whirlwinds, carrying dust, plants, and men to great heights—then suddenly dying away and leaving their reluctant passengers to fall to a horrible death
To replicate this, if a whirlwind appears, all character must make a Average (6+) STR roll to avoid being thrown 2D meters into the air. Falling damage will be 1D for every two meters. If a character makes a Average (6+) Survival roll they can detect the Whirlwind before it appears, giving them (and anyone they warn) a +1 on the STR roll.

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