Traveller: Dice & Strategy Guide

Traveller is one of the oldest science-fiction roleplaying games, and its modern editions keep an admirably clean resolution engine. Almost everything — piloting a ship through a tight orbit, patching a wound, talking down a nervous port official — comes down to rolling two six-sided dice, adding your modifiers, and meeting a target number. Once you have that rhythm, the whole game opens up.

The dice and the core mechanic

Traveller uses only six-sided dice. The standard task roll is 2d6 + a characteristic modifier (DM) + a relevant skill, compared against a difficulty target. Because you sum two dice, results form a gentle bell curve centred on 7, so modifiers carry real weight — every +1 is a meaningful shift in your odds rather than a rounding error.

Your characteristic modifier comes from ability scores such as Strength, Dexterity, Intelligence or Education; a score in the middle range gives +0, higher scores give a bonus and low scores a penalty. Your skill level adds directly, and an untrained attempt usually rolls at a penalty. The referee sets a difficulty for the task, with an Average task needing 8+ as the baseline that anchors the scale.

How a roll resolves

Roll 2d6, add your characteristic DM and skill (plus any situational DMs), and compare the total to the difficulty. The difficulty ladder runs roughly like this:

Meeting or beating the target is a success. What sets Traveller apart is Effect: the margin by which you beat (or miss) the target. Subtract the difficulty from your total and you get the Effect, a signed number that grades the outcome — a small positive Effect is a bare success, a large one is an emphatic one, and a negative Effect measures how badly a failure went. Effect feeds directly into combat damage, how much information you glean, how long a repair holds and much more, so a good roll is one that beats the target comfortably, not just barely.

Boon and Bane dice

Rather than piling on flat modifiers for every advantage, Traveller often uses Boon and Bane dice. When circumstances strongly favour you, you roll with a Boon: roll 3d6 and keep the highest two. When circumstances work against you, you roll with a Bane: roll 3d6 and keep the lowest two. A Boon and a Bane cancel out. Because they reshape which dice you keep, these are a strong, tactile swing — well worth engineering through preparation, the right gear or a clever plan.

Effective strategy

• Stack your DMs before you roll. With a bell curve centred on 7, the difference between +0 and +2 is enormous against an 8+ target. Combine a good characteristic, trained skill, the right equipment and a favourable situation, and an “Average” task becomes close to routine.
• Chase Effect, not just success. Since Effect drives damage and quality, a higher total is genuinely better. When a task feeds a later benefit, invest in the modifiers that push your Effect up rather than settling for a marginal pass.
• Use task chains. Many extended jobs let the Effect of one roll grant a DM to the next. Sequencing tasks — scout, then plan, then act — lets an early success snowball into a decisive one.
• Earn Boons, avoid Banes. Positioning, timing and the right tools can turn a straight roll into a Boon. Equally, recognise when you are about to roll with a Bane and consider improving your situation first.
• Play to your characteristics. Traveller characters are shaped by their careers and often have uneven scores. Steer problems toward the crewmate whose characteristic and skill line up, rather than having everyone attempt everything.

Beginner tips and common mistakes

• Don’t forget the skill penalty. Attempting a skilled task untrained usually carries a stiff negative DM. Know who on the crew is actually trained before committing to a risky roll.
• Read the margin. New players often stop at “did I hit 8?” The interesting part is by how much — note your Effect, because the referee frequently will.
• Modifiers are the game. On 2d6 you cannot rely on a lucky high roll; the reliable path to success is assembling bonuses. Treat gear, planning and teamwork as your real dice.
• Respect the setting’s lethality. Traveller combat and hazards can be unforgiving. A strong plan that grants Boons and avoids Banes beats charging in and hoping for sevens.
• Keep it light. The core loop is just 2d6 plus modifiers versus a target. You can run whole sessions on that alone before layering in ships, trade and the deeper subsystems.

Want another 3d6-style probability curve? Read our GURPS dice & strategy guide.