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Roll-and-Keep Task Resolution for Traveller

This article originally appeared in the November/December 2012 issue, and was reprinted in the May/June 2023 issue.

One of the things that I don’t like about most task systems for Traveller is that they require a decent amount of mental math, and the target number is different for each attempt. For example, the Traveller5 task system involves computing a target number (attribute + skill), adjusting that number up or down by adding and subtracting modifiers, and then rolling a number of dice based on the task difficulty.

I think that a task system that features less math and consistent target numbers might be better. I’m also favorably impressed by the “roll-and-keep” mechanic used by Legend of the Five Rings and 7th Sea (among others). So, here’s an attempt to bring that sort of game mechanic to the Traveller task system.

The basis of this task system is a roll-and-keep mechanic. Players roll a number of dice, keep some of the “best” dice (discarding the rest), and count up the pips. If the total matches or exceeds a target number, the attempt succeeds. If it does not, the task attempt fails. Target numbers are set by task difficulty, and do not change.


Before we can use the mechanic, players need to note some values on their character sheets for future reference—in essence, pre-computing key information needed to resolve tasks. This is necessary because Traveller uses different scales for attributes (2-12, with exceptional values up to 15) and skills (0 to 3, with exceptional values up to about 6).

To make the attribute values better align with skill levels, divide the attribute by 2 to find the equivalent number of dice. Drop fractions, or optionally represent the “half die” with a +1; record this value on the character sheet for future reference.

Example: Eneri has dex 7; he computes 7/2=3 and notes “dex 7 (3d+1)” on his character sheet.

The number of dice for each skill is equal to the skill level plus 1. Skill-0 becomes 1d, Skill-1 is 2d, Skill-2 is 3d, and so on. Record these values on the character sheet as well.

Example: Eneri has Pilot-2 and Pistol-0. He records “Pilot-2 (3d)” and “Pistol-0 (1d)” on his character sheet.

Tasks are stated the same way as in MegaTraveller and Traveller5, with a difficulty, duration, attribute, skill, and other information. The difficulty of the task determines the target number, as follows:

Table 1: Task Difficulty Target Numbers
Difficulty Target Difficulty Target
Easy 4+ Staggering 20+
Average 8+ Hopeless 24+
Difficult 12+ Impossible 28+
Formidable 16+ Beyond Impossible 32+

Rolling Tasks

The attribute and skill determine the number of dice rolled and kept. Look at the attribute and skill named in the task, and use the larger dice value as the number of dice rolled, and the smaller value as the number of dice kept.

Example: If Eneri attempts to shoot a target with his pistol, the task is based on dex and Pistol skill. The dice value for his dex is 3d+1, so he will roll 3d6 for the task attempt. His Pistol skill is worth 1d, so he will keep the best one of those three dice, and add one to it. If the total exceeds the difficulty target, he succeeds. Shooting from the hip like this, Eneri can hit the target on a pistol range (an Easy task) almost all of the time (96.3% success rate), but still has no chance of succeeding at an Average task.

Exploding Dice

Any kept dice that show a 6 “explode”, and the player may roll an additional kept die for each 6. These additional dice may also explode, resulting in more kept dice.

Favorable Modifiers

Favorable modifiers add additional dice to the player’s roll:

Minor Advantage Example: Bracing against a railing or building to steady his aim might give Eneri an additional unkept die. Now he will roll 4d6 for his pistol, but still keeps and counts up only one of those four dice.

Major Advantage Example: Taking a round to stand still and carefully aim might give Eneri an additional kept die. Instead of rolling 3 dice and keeping 1, he can now roll 4 dice and keep 2, dramatically improving his chances to hit.

Stacked Advantages Example: If Eneri braces (a minor advantage) and aims (a major advantage), he could roll 5 dice and keep 2, and now has a chance of hitting a Difficult target.

Unfavorable Modifiers

Remove an unkept die for minor obstacles. If the character has no unkept dice, these modifiers have no effect.

Example: Eneri is fighting in a dimly-lit warehouse, which costs him an unkept die. Now, instead of rolling 3 dice, he rolls 2 (and still keeps the best one).

Increase task difficulty for major obstacles, such as a hasty task.

Example: Eneri’s target is taking cover behind a cargo container; only the target’s head and arm are visible. This increases the task difficulty from Easy to Average. Eneri rolls and keeps the same number of dice, but must make a higher to-hit target.

Marginal Results

Most task attempts result in normal success or failure. If the task attempt hits the target number exactly, optionally treat this as a marginal success—the task very nearly failed, and only succeeded by the smallest possible amount. The referee should reduce the benefit of success if possible, for example by providing partial information.

Example: In combat, Eneri rolls a 4, against an Easy target of 4+, for marginal success. The referee rules that he has grazed the target, for half damage.

If the task attempt is only one below the target number, treat it as marginal failure: the task almost succeeded. The referee should minimze the negative effects of failure.

Example: In combat, Eneri rolls a 7 against a target number of 8+ for marginal failure. The referee rules that Eneri’s shot ricochets off the cargo container, mere centimeters from the target’s head—and forcing that particular henchman to duck behind the container and make a morale check next round.

Exceptional Results

If any of the kept dice show a 1 (single pip), then the task result is exceptional. If the task succeeds with a 1 showing, it is a critical success. The referee should award extra damage or other beneficial effects as appropriate to the task. Critical success trumps marginal success, so if a task succeeds in meeting the target number exactly with a 1 showing, it is critical success.

If the task result fails with a 1 showing, it is a critical failure, and may cause extra complications for the player. Marginal failure trumps critical failure, so that if a task is one short of the target number with a 1 showing on any of the kept dice, it is a marginal failure.

Comparison To Standard Traveller5

Table 2 shows a comparison of the chance of success in the standard Traveller5 task system vs. the Roll-and-Keep system presented here. An entry of Nil indicates that the chance of success is below 0.3%.

Table 2: Sample Percentage Chance of Success (Attribute 7, Skill 2)
Difficulty With No Modifiers With Minor Favorable Modifier With Major Favorable Modifier
Traveller5 Roll-and-Keep Traveller5 Roll-and-Keep Traveller5 Roll-and-Keep
Easy 100% 99% 100% 99% 100% 100%
Average 83% 75% 92% 90% 97% 95%
Difficult 38% 36% 50% 52% 63% 65%
Formidable 10% 11% 16% 22% 24% 33%
Staggering 2% 3% 3% 6% 6% 11%
Hopeless Nil Nil 0.5% 1% 1% 3%
Impossible Nil Nil Nil Nil Nil 0.5%