Task Rolls

A game of Traveller is played by a referee describing a situation, the players listen and respond and say what they what to do. A lot of the time there is no problem with what the players want to do. The game moves on, the referee describes a new situation and the players respond with new actions. But some times there is a chance that the players' actions will not succeed.

The original rules made a very simple suggestion on how to handle this, have the players roll two six sided dice, add bonuses for any relevant skills that they have and if the total is 8 or more they have succeeded, otherwise they have failed.

So:

     Roll 2 six sided dice + Relevant skill   =  8+ Succeed, otherwise failed

This is a very simple and 'rules lite' way of keeping the game moving and means the whole game can be played without barely having to consult the rules books and played in a way that is also very flexible.

You can literally try to do anything in Traveller. Want to fly a starship, making a daring leap, try and hack a computer? You have a simple way of handling it.

Built in probabilities of 2D6 System

Unlike a D20 system used in games like Dungeons and Dragons, that uses a twenty sided dice, Traveller's 2D6 (ie. Two six sided dice) system has a 'probability curve' built into it. Where as there is a completely regular distribution of results between 1 and 20 with a twenty sided dice, that is not the case with the addition of two six sided dice. Rolling two six sided dice and adding the results will produce a result between 2 and 12. But there is not a 1 in 12 chance of rolling two 6s to get 12. The chances are actually 1 in 36. On the other hand there are two ways you could roll an 11 (a 5 on one die and a 6 on the other, or 6 on one and 5 on the other) meaning there is a 2 in 36 or 1 in 18 chance of rolling an 11. The most common result when rolling two six sided dice is to roll a 7. There are six different ways you can roll a 7 (1 and 6, 2 and 5, 3 and 4, 4 and 3, 5 and 2, and 6 and 1). That means a 1 in 6 chance that any roll will producing a 7. So there is a built in bias to getting an average result.

Chances of success with 8+ dice roll (rounded to nearest 10%)

No skill                                               40%

Level 1 Skill  (Skilled/Trained)         60%

Level 2 Skill   (Highly Skilled)           70%
Level 3 Skill   (Expert level)              80%
Level 4 Skill   (Top Expert)                90%
Level 5 Skill   (Leading Expert)         97%

(Note if you apply a -3 unskilled penalty used in later editions chance of success for No Skill drops from 40% to 10%)

So the very simple Traveller 8+ task resolution system is cleverer than it looks.

The chances of rolling 8+ on two dice is around 40% (it is 42% to be exact). In simple terms the chances of success is a little under 50:50 and most likely to fail. 

But remember skill bonuses. With just a +1 bonus the chance of success moves up close to 60% (58% to be exact). Or in simple terms a bit better than 50:50, and most likely to succeed.

So simply having one level of skill tips the balance from being most likely to fail at a task to being most likely to succeed.

Having higher skill levels and therefore bonuses, moves the probability curve sharply in the characters favour. A +2 bonus makes the chance of success 72%, +3 increases it to 83%, and +4 to 92% virtually a certainty with just a very small chance of failure.

Remember the whole idea is there is no need to make a task roll for an action if it will in all probability succeed. The idea behind the original 8+ task roll system was that you only need to check for success or failure if it is uncertain and likely to be 'around 50:50'. So this system very subtly tips the odds slightly against characters without a relevant skill, and slightly in favour of those with a basic level 1 skill. It also sharply rewards those with skill levels above level one.

As a simple 'rule of thumb' the 8+ system using two die six is easy to remember, flexible and keeps the game moving. It means most players can try and do something, but characters with skills are most likely to succeed. You can very quickly define almost any task and come up with a way of resolving it. Need to open a lock with an electronic lock? Roll two dice, but your odds are a little higher than 50:50 that you'll fail. But if you have Electronics-1 skill you'll most likely succeed. A whole world of possibilities opens up. Having different skills will stimulate the players to ask to try imaginative things that there characters are already good at. Say you are in a grav car chase, you want to catch the car ahead. Roll for 8+ and the add grav vehicle skill, to succeed in catching it. Similarly  if it is you being chased roll for 8+ add grav vehicle skill and if succeed you have escaped, if you fail it is still on your tail.

Although later versions of Traveller added more complexity to the Task Resolution system, if you as a referee understand it, it is a quick and easy way of resolving something and keeping the game moving. There is no reason to use a more complicated method if you don't need it.

Roll equal to or under checks for Strength, Dexterity etc...

Before going on to describing those more complicated task resolution systems in later rule systems, there are a couple of other points to address.

First it maybe worth mentioning character's characteristics, Strength, Dexterity, Endurance and so forth. The original Traveller rules didn't really explain what to do with them. Traveller's creator Marc Miller did though suggest a simple way to use them in task resolution. Again the assumption is the basic chances of success are around 50:50. And again remember the characters characteristics were all generated also with two six sided dice and are all measured around a baseline average of a score of 7. So if a task is clearly basically about using strength, dexterity, intelligence or one of the other characteristic rolls just roll two six sided dice, and if the result is equally to or BELOW their characteristic score in this characteristic you have succeeded, otherwise you have failed.

So need to shift a big heavy rock to get through a mine passage? Make a strength test, roll two six sided dice and if the roll if equal or less than the character's strength they have moved it, otherwise they have failed. Running around in a rooftop chase and want to make a daring leap between two buildings? Roll two six sided dice and try to roll the character's dexterity or less. Need to resolve some tricky problem that requires intelligence or general knowledge? Check against a character's intelligence or education. Want to get into some exclusive night club? Check against Social Status.

This was mentioned in later editions of the rules, but you have to look hard to find it. But it is a quick and easy way of resolving tasks and as a referee it is worth bearing it in mind before looking for a more complicated task resolution system.

There is also a quick and easy way of adjusting the difficulty on one of these 'roll under' checks against characteristics. If you want to make the task easier have the players roll only one six-sided die not two. Want to make it more difficult roll three dice not two. This in fact is the basis of task resolution in Marc Miller's favourite development of the Traveller, the T5 edition.

Zero level skills introduced in later editions, a good idea?

The next point to make is about whether skills are necessary to do certain tasks. It is worth remembering as a referee that you should think of the default position as being that players should be able to try to do anything, it is just if you lack a necessary skill you are more likely to fail than succeed, but if they have a relevant skill the odds are in their favour. In an advanced technological society a player doesn't need computer skill to use a computer, but Computer skill will help with a difficult task like hacking. So don't automatically assume that a player can't do something just because they lack a skill in it. You can still try to offer a bribe without Bribery skill, it is just if you have Bribery skill it is more likely to succeed. On the other hand certain skills are 'qualifications'. Most people probably won't try and fly a plane without a lot of training. The 'Pilot' skill qualifies a character to pilot a starship or spacecraft. So fairly obviously a character without at least Pilot-1 skill is not going to be able to do it. You might as a referee want to let an unskilled character try, but with the 8+ task resolution system the odds are they will fail any Pilot task, and end up crashing.

But the original rules did leave it a little bit ambiguous in some areas, whether if you lacked the skills you could do the task. It didn't help that in some versions of the Classic Traveller rules it was suggested you apply a -4 penalty if a character lacked the necessary skill. So which was it, roll for 8+ with no bonus, or roll with a -4?

In later versions of the rules the idea of zero level skills was introduced. The idea of zero level skills was to clear up ambiguity about whether or not you suffered a penalty. Zero level skills were generally given as background skills, often based on the character's home world. So if a character came from a mid-tech world they might get Wheeled Vehicle-0, if they came from a high-tech world Grav Vehicle-0 and Computer-0, if they were from an Asteroid Belt or Vacuum World they might get Vacc Suit-0. Players always like getting more skills. But if they cleared up a certain amount of ambiguity, they can also introduce the idea into referees and players' heads that without a relevant skill your character cannot do something. That was not the intention of the original rules, and the 8+ task system already builds in a higher chance of failure for lacking skills.

From roll 8+ to variable difficulty level introduced in later editions...

Ultimately, eventually an edition of the rules came along that questioned whether the 8+ system was varied enough. The MegaTraveller rule set actually invented the idea of a whole Task System rather than just a Task Roll. A referee didn't just have to go with the 8+ system. They could decide if a particular task was Easy, Routine, Difficult, Very Difficult or near Impossible. It encouraged giving bonuses for characteristics as well skills, considered Exceptional Success and Exceptional Failure, Mishaps, the effect of failing at Hazardous Tasks, and opposed Tasks. If you like a complex Task System this system was for you. But it lost the basic simplicity of the roll 8+ system.

The net result was later systems such as Mongoose Traveller and Cepheus Engine reverted to the 8+ system, but contained guidance for adjusting it.

For example in Cepheus Engine there is a whole table with suggestions for adjustments to make a Task 'Easy', 'Routine', 'Difficult', 'Very Difficult' and so on. The rules also introduce the idea of Effect, using the difference between the score needed and actually rolled to make other adjustments. For example, on a combat roll the Effect on the 'To Hit' roll can be used to score additional damage.

Imports from D&D5e. A good idea or just screwing with a system that worked better without them?

The final thing that has happened with modern versions of the rules is standard bonuses and penalties for different characteristic levels have been introduced. The idea has come from the more recent editions of Dungeons & Dragons, that introduced the idea of a Strength Check, Dexterity Check, Intelligence Check and so forth, rolled with standard bonuses based on those characteristics. It fact Traveller already had its own system for Strength Checks, Dexterity Checks and so forth long before it was ever thought of in D&D, the roll under system described above. But players coming into the game from D&D wanted something familar and Mongoose Traveller gave them what they wanted in the form of standard bonuses and penalties based of characteristics. It encouraged referees to define tasks as being Strength-based, Dexterity-based, Intelligence-based and so forth, and as well as adding skill bonuses add these characteristic bonuses and penalties too. In my view a system like this can produce some odd results. Consider a situation where there are two characters one with no medical skill the other with Medic-2. Now let's say they each need to treat a dying patient in an effort to keep them alive. In the basic roll 8+ adding skills system, the character with no medical skill would have a 42% chance of success, the one with Medic-2 a 72% chance. But if you put characteristic bonuses or penalties into the mix this could turn it all around. The characteristic you choose could be Dexterity or Intelligence or Education. But what if the character with no medical skill has a +2 characteristic bonus and the one with Medic-2 a -1 penalty? Suddenly the character with no medical skill has a higher chance of success than a highly experienced medic. That makes no sense to me. So my advice is to use this system with care. It is a 'foreign import' to the core roll 8+ system that Traveller was designed around and can produce some strange results.

The other D&D 5e import that Mongoose Traveller 2nd edition introduced was 'boons' and 'banes'. The basic idea is that you can make tasks easier or harder by allowing them to roll 3 dice rather than 2 and choosing the highest two, or make tasks harder by allowing players to roll 3 dice and making them discard the highest one.

The system has the advantage of being simple and easy. The question is whether it is really necessary. Isn't it easier just to add or deduct a bonus like the difficulty system?

Basically it is up to the referee. A statistician would probably tell you it is basically just a different way of doing the same thing, but this is a tabletop game and rolling dice is fun, so it is up to you.

Advice to referees - Only add later complications if you need them. Roll 8+ works 90% of the time!

So in conclusion Traveller came with a very simple and effective Task Roll system of roll two six sided dice, add bonuses for skills and try and roll 8+. The system was based on only rolling where the outcome is uncertain, and around 50:50. It is a system that is cleverer than it looks and works well, is easy to remember, highly flexible and keeps the game moving without the need to keep looking in rule-books.

There is also a simple 'roll equal to or under' system for checks against the basic characteristics like Strength, Dexterity, Intelligence etc..

Later editions have introduced options for adjusting difficulty levels of tasks, taking into account Effect and adding standardised bonuses for characteristics like Strength etc..

But bear in mind the basic system works and works well with the whole skill system and you don't need to introduce more complexity than you need.

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For those interested in adjusting the difficulty level of tasks these are the recommendations of the Cepheus Engine rules:

Simple           +6

Easy              +4

Routine          +2

Average - normal 8+ roll

Difficult           -2

Very Difficult   -4

Formidable      -6

A roll 6 or more above the required score is considered an 'Exceptional Success' and 6 or more below an 'Exceptional Failure'.

The difference between the score required and the score actually rolled is called the Effect.

In Cepheus Engine the standard characteristic (eg. Strength, Dexterity, etc.) bonuses and penalties are as follows:

C+ (12+)  +2

9-11         +1

6-8             0

3-5           -1

2              -2


Cepheus Engine also zero level skills (eg. Vacc Suit-0). There is a -3 penalty for being unskilled.