Let's Read “Traveller: Core Rulebook - Encounters and Dangers”

In Space, Dangers are More Varied

In the previous chapter we dug into Traveller’s Combat. In this chapter we get an overview of environmental dangers, recovery, and encounters.

I’ve often run single world fantasy games. A presupposition is that there is adequate oxygen to breath, gravity behaves much like earth, and people move about their lives in an environment native to their biology.

Environmental Dangers

I find the opening paragraph helpful in framing environmental dangers:

Most life-bearing worlds feature biology completely incompatible with alien visitors, so Travellers are utterly unaffected by their native pathogens. The exceptions are typically planets where everything is inimical to human life. Alien diseases that affect humans are comparatively rare, most of which are mutations or engineered variants of diseases originally from Earth. Panacea drugs can aid the immune system resist infection on unfamiliar worlds. Poisons are rarer, but more dangerous – injecting an unfamiliar chemical into your bloodstream is never a good idea.

In 2020, living through a pandemic, it’s important to frame a pre-supposition about the worlds that Travellers will encounter.

As role-playing games are often times adventure games, we need to consider the hazards of the environments in which Travellers adventure.


A common trope of science fiction is disease. The rules are relatively straight forward. To resist a disease make an Endurance (End 🔍) check. When you fail, you contract the disease and take damage and must continue to make End checks at the specified interval. Once you succeed, you’ve overcome the disease.

Table 201: Traveller Example Diseases
DiseaseEND check DifficultyDamageInterval
AntrhaxVery Difficult (12+)2d61d6 days
Biological WeaponFormidable (14+)3d61d6 hours
PneumoniaAverage (8+)1d61d6 weeks
Regina FluRoutine (6+)1d6-21d6 days

From the above table of example diseases, we can extrapolate other diseases.

I assume, when we get to the Healing subsection, we’ll get guidance on how treatment can help with overcoming disease.


By default you take 1d6 damage per 2 meters fallen. Higher or lower gravity changes this. The Effect of a successful Athletics check reduces the effective falling distance by a like number of meters. Aside from the caveat regarding gravity, this appears to be rather standard fare. I’d imagine that someone could calibrate characters and games systems entirely based on the rules for falling damage.


Physical activity and lack of sleep can induce fatigue; The book provides a few recommendations. A fatigued Traveller has Bane on all of their checks. Drugs can help overcome fatigue. And referees can say after a certain point a fatigued character falls into unconciousness. These rules seem adequate as guidelines and framing for fatigue. As a referee, I usually prefer some kind of test before forcing a character unconcious. Typically, I’d frame this as: “You’ve been doing all of this while fatigued. And you want to push for this one thing. Let’s look at this as a . First make an Endurance check, failure means you’re going to fall unconcious after the next task. The Effect of the Endurance check will modify the check you’re about to make. Are you still wanting to try?” This echoes Apocalypse World’s Act Under Fire move.


These operate similar to diseases, but at a faster interval. The example poisons expand the range of damage. I’ll need to keep an eye out for how to apply Intellect damage. I assume that dropping to 0 Intellect would either render someone unconcious. The only prior reference I recall is related to an Aging Crisis during character creation.

Table 202: Traveller Example Poisons
PoisonEND check DifficultyDamageInterval
ArsenicDifficult (10+)2d61d6 minutes
Tranq gasDifficult (10+)Unconcious1d6 seconds
NeurotoxinVery Difficult (12+)1d6 Intellect1d6 seconds


A reminder of the affects of different degrees of gravity. How you acclimate over time. A Traveller trained in Athletics (strength) acclimates immediately to higher gravity. Likewise a Traveller with Athletics (dexterity) immidately acclimates to lower gravity. Note, these assume “safe levels” of gravity. I’d imagine no human could acclimate to 12G.

In zero gravity, Athletics (dexterity) helps you control your movement. Attacking with a ranged weapon that has recoil or a melee weapon could set you spinning.


On early 21st Century Earth we take for granted the lack of radiation. However, without the Earth’s protective magnetic field, Travellers need to consider the dangers of radiation. This is my first encounter with a system that tracks radiation. Certainly something interesting to consider.

By the rules, radiation accumulates over time. Only during significant events do you track radiation. Its assumed standard travel in a shielded ship is negligible. But flying to close to the sun, suffering a reactor leak, a breached hull, or something else would add radiation to your cumulative track. You only rid yourself of accumulated radiation by taking anti-radiation drugs.

Table 203: Traveller Radiation Effects
Radiation ExposureImmediate EffectCumulative Effect
50 rads or lessNoneNone
51 to 150 rads1d6 damage, Nausea (-1 to all checks until you receive medical treatment)None
151 to 300 rads2d6 damage-1 End permanently
301 to 500 rads4d6 damage, hair loss-2 END permanently
501 to 800 rads6d6 damage, sterile-3 END permanently
801 rads or more8d6 damage, internal bleeding-4 END permanently

Needless to say, it’s quite evident that radiation is a very useful countdown clock. I think about the clocks in Blades in the Dark; Those clocks very much model the radiation danger. Mechanically, no player wants to watch their character’s stats drain away.

Also of note, its -1 End then -2 END, for a total of -3 END.


In a spaceship, you need life support. Here Traveller introduces us to a ships life support capacity.

A spacecraft or self-contained, sealed structure with power can usually sustain life support for one person per stateroom for one month comfortably, and for six months at a stretch (number of staterooms x 5,000 person/hours). Without power, this drops to two weeks at most. Various shelters will list the amount of air and life support available if they differ.
Traveller: Core Rulebook p77-78

I assume we’ll learn more about a “stateroom” in a future chapter. Hint: we do.

Suffocation due to failed life support is 1d6 damage per minute. Drowning or a complete lack of oxygen is 1d6 damage per six seconds. It takes a bit of mental re-framing to think about Endurance as a direct durability score. In some ways, it’s very much analogous to the ubiquitous hit points. I supposed I’m a bit conditioned to assume that suffocation starts after a certain time, then you begin making checks to endure. In Traveller, the system immediately starts degrading your attributes. I believe the direct nature of Traveller may help players better see the looming danger and consequences.


Without protective gear, hot and cold places do damage. The more severe, the faster the damage interval.


The vacuum of space is quite dangerous. Without a vacc suit, you suffer escalating damaging (e.g. 1d6 the first round, 2d6 the second, 3d6 the third, etc.) and you suffer 2d6×10 rads per round. Yikes!


And remember high winds, driving rain, and general incliment weather can be dangerous. Especially when conditions are atypical to our expectations (e.g. walking on a carbon dioxide glacier may melt in the footsteps of a Traveller).

Psst, Referee, this is not the time to play “gotcha.” Assume your Travellers know about these kind of dangers. Don’t require that they think of everything. Instead if the Travellers are reasonably equipped (e.g. have sensors), offer up this information. Telegraph that the environment may complicate things. In a Powered by the Apocalypse game, this is where you “Announce future badness.” Players may not know all the details of stellar geography, but a Traveller with any training in Survival or Science likely has some basic knowldege. In other words, be generous in your information, tell them about the melting carbon dioxide, and ask them what they do.


Now that we’ve went through combat and dangers, lets see how you get better. I believe this will require a careful reading.

We have two sub-sections: Medical Treatment and Natural Healing.

A Traveller can receive First Aid within a minute of injury. Here, I’d rule “By the end of the scene” instead of within one minute of sustaining an injury. You regain characteristic points equal to the effect of a medic task; You divide the effect between your damaged characteristics. Implicit in the warning about medical treatment is that a negative effect will cause further damage. However, that is not explicit. So, be kind, and don’t inflict more damage to the poor Traveller.

Assuming you still have three damaged characteristics, you require surgery. Surgery requires a hospital or sickbay. Similar to First Aid, on a success you regain characteristic points equal to the effect. On a failure, you take 3 points of characteristic damage increased by the negative effect (e.g. if you fail by 2, you take 5 points of damage).

Once at least one characteristic is back to its maximum level, the patient may benefit from medical care (and begin natural healing).

In medical care, your Traveller regains characteristic points equal to 3 + End Dungeon Master (DM 🔍) + doctor’s Medic skill. These points must be distributed evenly.

And if you have augmentations, recovery at a facility of a lower Technology Level (TL 🔍) than your augmentation imposes penalties equal to the TL difference.

Mental characteristic damage heals at a rate of one point per day.

For natural healing, if you don’t require surgery (e.g. damage to no more than 2 physical characteristics) you regain 1d6 + Endurance modifier per day of full rest.

If you need surgery, you only regain your Endurance modifier (which if negative means you lose characteristics).

Seeing the interplay of damage, dangers, and example weapons, it’s quite clear that Traveller is dangerous and recovery requires medical attention. No “8 hour long rest” and you’re healed up.


Traveller provides a chart for determining encounter distance. This reminds me of the procedures for earlier editions of Dungeons and Dragons.

The rules give a brief description about Recon vs Stealth as well as opposed Technology.

All told, a short yet useful section for Sandbox play.


Traveller provides a quick overview of animals, how to construct them, and four examples.

Most interesting is the Fight or Flight table. I can see repurposing this for many games. To determine their reaction, roll 2d6 and consult their animal type.

Seriously look at this table with an eye on an NPC’s approach or instinct. A “filter” NPC might be someone drifting through life. A “pouncer” might be a mugger.

Table 204: Traveller Fight or Flee
Animal TypeFleeFight
Filter5-10+ if possible
Hunter5-If the animal is of greater Size, attacks on a 6+. Otherwise, attacks on a 10+
PouncerIf surpised, fleesIf animal has surprise, attacks
Chaser5-If animals outnumber prey, attack
Trapper5-If animal has surprise, attacks
Siren4-If animal has surprise, attacks

This table along with the brief description regarding each animal type provides a useful reaction table for animals. It’s also something immediately useful for non-player characters.

A random encounter leads to a scavenger ship, they typically pick clean what ever remains. On the above chart, they’re a reducer.

Other Characters

We get a quick run-down of non-player characters. Here we get a bit more information about those Allies, Contacts, Rivals, and Enemies generated during character creation. There’s a brief bit about skill allocation. While this isn’t in the book, I’d use the career assignments, and make sure the NPCs have ranks in Service Skills and their Assignment.

Allies will take significant risks for your Traveller. Once per game year you can call on an Ally’s aid. I could easily see an Ally becoming a replacement character.

Contacts will provide limited help. They won’t risk much, but will point the Traveller in the right direction.

Rivals and Enemies. Both create barriers for the Travellers. An Enemy will just go further than a Rival.

The book advises making Enemies and especially Rivals mobile. After all, its great grist for the story mill if you keep getting undercut by a rival broker.

Patrons and Missions

This brief section talks about using NPCs as employers of the Traveller. And we get some Randome Encoutner tools to quickly roll up a high-level overview of a Mission.

Random Encounters

The following five tables provide some randomization to get you unstuck. I know I like rolling on a few random tables to seek information on how to frame a scene or scenario.

  • Allies and Enemies
  • Character Quirks
  • Random Opposition
  • Random Patrons
  • Random Mission
  • Random Targets

These days, when I’m running a game, I have lots of random tables at my call. I tend to use Stars without Number: Revised Edition 🔍’s various random tables. I’ll add these to my toolbox.

Payments for Missions

My understanding is most Traveller games involve a bit of trading. In the Payments and Missions sidebar we get some solid advice: “A wise patron should always offer the Travellers more than they can get by trading.”

Once the Travellers start plying the trading lanes, they’re going to need some serious cash or leverage to consider other options.


A bit broader in scope than what I’m used to reading, but useful. This section helps the referee think about varied difficulties and challenges.

I love the radiation section as well as the Fight or Fleet table. The radiation helps the referee introduce a clock.

Up next, we’ll dive into .