**Introduction: So what's wrong with the T4 Task System?**

Anyone who has played Traveller using the task system published in T4 will have noticed that there are serious problems with it. The most obvious is that characters with high statistics are too powerful. This is only partly due to the character generation system, which makes it easy to accumulate high statistics - a maximum Education stat in particular. But the main problem is the relative weight given to PC characteristics over skill levels. For instance, a PC with a Dexterity of 14 and a weapon skill of 1 has a better chance of hitting than a PC with Dexterity 7 and weapon skill of 6. The game designers' explanation is that characteristics provide the base ability, while training in skills just enhances that ability.

I agree that characteristics should be important, but I (and many other participants on the Traveller Mailing List) feel that vastly superior training in skills should count for more than superior natural ability. Almost any character with a skill of 6 should be able to best someone with a skill of only 1, no matter how high their applicable characteristic.

A look at the statistical probabilities for many typical task rolls reveals other serious problems. Probabilities seem sensible enough for PCs with low characteristics and skills, but as the target numbers climb, certain tasks become too 'easy'. Difficult Tasks (of prime importance in combat) are too easy for characters with high stats, regardless of their skill levels. For instance, Difficult tasks are automatic for any PC with a stat of 14 and skill of only 1. Even Impossible Tasks are all too possible (even taking into account that the term 'Impossible' is intended to mean 'Almost Impossible').

For example: in a recent game, my character single-handedly repaired most of the major systems of a mostly-trashed starship (an Impossible Task), armed only with Engineering 1, a tool box...and an Education of 15. My target number was 16, giving me a 73% chance of success on 4D! Even though I had to roll separately for each system I repaired, I didn't fail once. And this character was an archeologist, not a professional ship's engineer!

Other problems are mere annoyances that soon become major headaches. The half-die (D3) introduced in T4 is one of these. It slows down the game and, as Marc Miller pointed out on the TML, player honesty becomes an issue, if there is any doubt as to which die intended as the half-die. Even if a task-system fix were found that eliminates half-dice entirely, the T4 system still involves throwing too many dice. And most of the fixes suggested on the mailing list suggest adding *more dice* to the rolls, sometimes as many as ten dice for an Impossible task! This is getting ridiculous.

These proposed task system fixes seem to me to make things too difficult for characters with lower-than-average stats (which is any injured character). Also, it's difficult to predict how probabilities will change when dice are added to a task, and this is one of the main problems with T4 and its variants. With increasingly steep bell curves, for certain combinations of stat and skill there is almost no difference in probability between Impossible and Staggering, or between Staggering and Formidable. And sometimes an increase of one skill level makes a big difference, sometimes very little, depending on how many dice are being thrown.

Further, there's no simple way of dealing with Spectacular Successes when rolling different numbers of dice for each level of Difficulty. The original T4 system (taking any two ones or sixes as a Spectacular result) actually makes Spectacular Success more likely as the tasks become more difficult - an absurd idea. Various fixes can be suggested, but now things are getting increasingly complicated.

Looking at the problem, one is tempted to throw it all out and use a percentile system. Rolling two D10 for a 01-100 range is straightforward and intuitively easier. But converting all the rules from the D6-only system of T4 to a percentile system would involve too much work.

However, we can have many of the advantages of a percentile system while sticking with D6s: roll one D6 for a 'tens' digit, and a second for a 'ones' digit, for a result between 11 and 66 (just like rolling on the cargo table in Classic Traveller). Target numbers should be relatively easy to work out: note that there are six Levels of Difficulty (from Easy to Impossible); we can say that the tens digit is defined by the Difficulty level. Then we add modifiers for stats and skills.

And that's the basic concept of this system - though in practice it's a bit more complicated. Stat and skill modifiers have to be added in base-6, which can seem confusing at first. To make things easier, a pre-calculated Task Number Table is included here, though it shouldn't be necessary once players are familiar with the system.

The beauty of this concept is that we've done away with the 'bell curve' (the bell-shaped distribution of probabilities that results from adding multiple dice together). It becomes much easier to predict how skills or stats or changes in Difficulty level are going to effect the probability of success. For those who feel that bell curves are necessary to accurately model "reality", I would point out that character stats still follow a bell curve (though skewed towards the high end, I would bet), so such curves have not been completely eliminated from the game system.

A summary of the benefits of the D66 Task System:

- only two dice are rolled for all tasks,
- no half-dice,
- skill levels count for more than stat points; (stat to skill ratio is 3:1),
- target numbers can be calculated before play begins, or on the fly,
- characters with high stats and/or skills are not super-powerful,
- characters with low stats and/or skills are not too weak,
- similar to a percentile system, hence more intuitive,
- no pesky bell curve,
- each increase in difficulty represents an equal decrease in probability,
- each increase in skill or stat represents an equal increase in probability,
- easily modified to suit situation, taste, style of game.

This system assumes an upper limit to Skill Levels of about 10 (though the TN Table shows only 0 to 8). If your game involves PCs with higher Skill Levels, or if you think that a Stat to Skill ratio of 1:3 is too high, I suggest using a Stat to Skill ratio of 2:1 instead. In this case, add 1 to the first digit of the Base Target Numbers shown below the Formula.

Note that there is no built-in upper limit on attributes in this system, which can easily accomodate characters with attributes above 16, such as robots, aliens, variant human species, or prosthetically augmented humans. The absolute upper limit is probably 24. (A character with stat 20 and skill 1 has a Difficult TN of 65 (98%), Impossible 35 (47.6%).

Note also that it is very easy to add further levels of Difficulty - "Beyond Impossible", "Insane", "Suicidal", etc - simply by subtracting from the first digit of the TN. This is particularly useful when dealing with super-powered PCs. And it doesn't require thowing bucketfulls of dice.

IMPORTANT: this system has a higher 'granularity' than the T4 system. As a result, the DMs given in the books are likely to have less affect on the outcome of a roll. For instance, a PC with Dexterity 12 and Pistol 4 makes a Called Shot for Double Damage at effective range. In T4, his base Target Number is 16, DM-5 for the Called Shot, for a TN of 11. His usual chance of success is 73.3%, but with the DM it is 23.9%; the difference is 49.4%. In the D66 system, his usual TN is 55 (81.2%); with the DM it is 46 (67.2%): the difference is only 14%. Obviously most DMs are going to need adjusting. In the D66 Target Number Formula, skills levels are multiplied by 3 to give the Skill Modifier; therefore, all DMs given in the rules should also be multiplied by 3. Thus the DM-5 for the Called Shot becomes DM-15, giving our character a TN of 32 (39.2%). The difference is now 42%, much closer to what the game designers intended.

Where the T4 rules call for increasing the Difficulty one Level, instead of throwing more dice, just subtract 1 from the first digit of the TN.

If you try this system, please do let me know how it works for you. In
particular, let me know if you encounter any T4 rules that are incompatible
with it. *[Editor's Note - This is one of the things that you can and
should use the Feedback page for.]*

**The D66 Task System - Mechanics**

The task roll is always two dice, pre-selecting one die for 'tens' and the other for 'ones'. As in T4, the task is successful if the player rolls the Target Number (TN) or less.

Consult the Target Number Table, or use the formula (below the Table) to calculate Target Numbers.

NOTE: For 0-Level Skills, do not halve the attribute. (Instead, Difficulty is increased by one level, by simply subtracting 1 from the first digit of the Base Target Number).

As always, a roll of two sixes is a Spectacular Failure, and two ones is a Spectacular Success - even if the target number is below 11.

On the table, "I S F D A E" means Impossible, Staggering, Formidable, Difficult, Average, Easy.

Below the appropriate Skill/Difficulty Level, find the appropriate Stat Code (in hexadecimal), which will provide the TN, at left. TNs for Stats above F are not shown, but are easy to extrapolate. The "Stat Only" column gives TNs for unmodified attribute tests. Multiply all other DMs given in the rule books by 3. At right is a rough calculation of the statistical odds.

**Target Number Table**

-Skill 0- -Stat Only- --Skill 1-- --Skill 2-- --Skill 3-- TN S F D A E I S F D A E I S F D A E I S F D A E I S F D A E % ----------------------------------------------------------------------- 11 E 8 2 - - E 8 2 - - - B 5 - - - - 8 2 - - - - 5 - - - - - 2.8 12 F 9 3 - - F 9 3 - - - C 6 - - - - 9 3 - - - - 6 - - - - - 5.6 13 A 4 - - A 4 - - - D 7 1 - - - A 4 - - - - 7 1 - - - - 8.4 14 B 5 - - B 5 - - - E 8 2 - - - B 5 - - - - 8 2 - - - - 11.2 15 C 6 - - C 6 - - - F 9 3 - - - C 6 - - - - 9 3 - - - - 13.0 16 D 7 1 - D 7 1 - - A 4 - - - D 7 1 - - - A 4 - - - - 16.8 21 E 8 2 - E 8 2 - - B 5 - - - E 8 2 - - - B 5 - - - - 19.6 22 F 9 3 - F 9 3 - - C 6 - - - F 9 3 - - - C 6 - - - - 22.4 23 A 4 - A 4 - - D 7 1 - - A 4 - - - D 7 1 - - - 25.2 24 B 5 - B 5 - - E 8 2 - - B 5 - - - E 8 2 - - - 28.0 25 C 6 - C 6 - - F 9 3 - - C 6 - - - F 9 3 - - - 30.8 26 D 7 1 D 7 1 - A 4 - - D 7 1 - - A 4 - - - 33.6 31 E 8 2 E 8 2 - B 5 - - E 8 2 - - B 5 - - - 36.4 32 F 9 3 F 9 3 - C 6 - - F 9 3 - - C 6 - - - 39.2 33 A 4 A 4 - D 7 1 - A 4 - - D 7 1 - - 42.0 34 B 5 B 5 - E 8 2 - B 5 - - E 8 2 - - 44.8 35 C 6 C 6 - F 9 3 - C 6 - - F 9 3 - - 47.6 36 D 7 D 7 1 A 4 - D 7 1 - A 4 - - 50.4 41 E 8 E 8 2 B 5 - E 8 2 - B 5 - - 53.2 42 F 9 F 9 3 C 6 - F 9 3 - C 6 - - 56.0 43 A A 4 D 7 1 A 4 - D 7 1 - 58.8 44 B B 5 E 8 2 B 5 - E 8 2 - 60.6 45 C C 6 F 9 3 C 6 - F 9 3 - 64.4 46 D D 7 A 4 D 7 1 A 4 - 67.2 51 E E 8 B 5 E 8 2 B 5 - 70.0 52 F F 9 C 6 F 9 3 C 6 - 72.8 53 A D 7 A 4 D 7 1 74.6 54 B E 8 B 5 E 8 2 78.4 55 C F 9 C 6 F 9 3 81.2 56 D A D 7 A 4 83.2 61 E B E 8 B 5 86.0 62 F C F 9 C 6 88.9 63 D A D 7 91.7 64 E B E 8 94.5 65 F C F 9 97.3 66 D A 100.0 --Skill 4-- --Skill 5-- --Skill 6-- --Skill 7-- --Skill 8-- TN I S F D A E I S F D A E I S F D A E I S F D A E I S F D A E % ---------------------------------------------------------------------- 11 2 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 2.8 12 3 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 5.6 13 4 - - - - - 1 - - - - - - - - - - - - - - - - - - - - - - - 8.4 14 5 - - - - - 2 - - - - - - - - - - - - - - - - - - - - - - - 11.2 15 6 - - - - - 3 - - - - - - - - - - - - - - - - - - - - - - - 13.0 16 7 1 - - - - 4 - - - - - 1 - - - - - - - - - - - - - - - - - 16.8 21 8 2 - - - - 5 - - - - - 2 - - - - - - - - - - - - - - - - - 19.6 22 9 3 - - - - 6 - - - - - 3 - - - - - - - - - - - - - - - - - 22.4 23 A 4 - - - - 7 1 - - - - 4 - - - - - 1 - - - - - - - - - - - 25.2 24 B 5 - - - - 8 2 - - - - 5 - - - - - 2 - - - - - - - - - - - 28.0 25 C 6 - - - - 9 3 - - - - 6 - - - - - 3 - - - - - - - - - - - 30.8 26 D 7 1 - - - A 4 - - - - 7 1 - - - - 4 - - - - - 1 - - - - - 33.6 31 E 8 2 - - - B 5 - - - - 8 2 - - - - 5 - - - - - 2 - - - - - 36.4 32 F 9 3 - - - C 6 - - - - 9 3 - - - - 6 - - - - - 3 - - - - - 39.2 33 A 4 - - - D 7 1 - - - A 4 - - - - 7 1 - - - - 4 - - - - - 42.0 34 B 5 - - - E 8 2 - - - B 5 - - - - 8 2 - - - - 5 - - - - - 44.8 35 C 6 - - - F 9 3 - - - C 6 - - - - 9 3 - - - - 6 - - - - - 47.6 36 D 7 1 - - A 4 - - - D 7 1 - - - A 4 - - - - 7 1 - - - - 50.4 41 E 8 2 - - B 5 - - - E 8 2 - - - B 5 - - - - 8 2 - - - - 53.2 42 F 9 3 - - C 6 - - - F 9 3 - - - C 6 - - - - 9 3 - - - - 56.0 43 A 4 - - D 7 1 - - A 4 - - - D 7 1 - - - A 4 - - - - 58.8 44 B 5 - - E 8 2 - - B 5 - - - E 8 2 - - - B 5 - - - - 60.6 45 C 6 - - F 9 3 - - C 6 - - - F 9 3 - - - C 6 - - - - 64.4 46 D 7 1 - A 4 - - D 7 1 - - A 4 - - - D 7 1 - - - 67.2 51 E 8 2 - B 5 - - E 8 2 - - B 5 - - - E 8 2 - - - 70.0 52 F 9 3 - C 6 - - F 9 3 - - C 6 - - - F 9 3 - - - 72.8 53 A 4 - D 7 1 - A 4 - - D 7 1 - - A 4 - - - 74.6 54 B 5 - E 8 2 - B 5 - - E 8 2 - - B 5 - - - 78.4 55 C 6 - F 9 3 - C 6 - - F 9 3 - - C 6 - - - 81.2 56 D 7 1 A 4 - D 7 1 - A 4 - - D 7 1 - - 83.2 61 E 8 2 B 5 - E 8 2 - B 5 - - E 8 2 - - 86.0 62 F 9 3 C 6 - F 9 3 - C 6 - - F 9 3 - - 88.9 63 A 4 D 7 1 A 4 - D 7 1 - A 4 - - 91.7 64 B 5 E 8 2 B 5 - E 8 2 - B 5 - - 94.5 65 C 6 F 9 3 C 6 - F 9 3 - C 6 - - 97.3 66 D 7 A 4 D 7 1 A 4 - D 7 1 - 100.0

Example: A character with skill 3 and characteristic 9 is attempting a difficult task. We look at the "Skill 3" column group, and specifically under the "D" column. We follow this column down until we find the stat value of 9, then we follow that row to the left, where we find that the target number is 45.

Alternatively, here's a table showing the TNs for Stat 7. Numbers in brackets are automatic tasks. SO = Stat Only, for straight tests of attributes, without added skills. For each stat point above 7, add 1 to these Target Numbers (in base-6). For each stat point below 7, subtract 1 (in base-6).

**Target Number Table**

Stat = 7 Skill 0 SO 1 2 3 4 5 6 7 8 9 10 Easy 36 46 53 56 63 (66) (73) (76) -- -- -- -- Avge 26 36 43 46 53 56 63 (66) (73) (76) -- -- Diff 16 26 33 36 43 46 53 56 63 (66) (73) -- Form 16 16 23 26 33 36 43 46 53 56 63 (76) Stag -16 06 13 16 23 26 33 36 43 46 53 66 Imps -26 -16 03 06 13 16 23 26 33 36 43 56

**The Target Number Formula: **Target Number = BTN +
(skill*3) + (characteristic-7)

So, to determine the target number for a task:

- Determine the Base Target Number (BTN)
**Difficulty Level****BTN**Impossible -16 Staggering 06 Formidable 16 Difficult 26 Average 36 Easy 46

- Modify the BTN by the PC's skill and by the corresponding
characteristic.
- +3 for each skill level.
- +1 for each characteristic point above 7; -1 for each point below 7.
- All DMs given in the rule books should be multiplied by 3.

NOTE, however, that these modifiers are not added in base-10. The modifiers are counted as steps up or down the 11-66 matrix:

-11 -12 -13 -14 -15 -16 01 02 03 04 05 06 11 12 13 14 15 16 21 22 23 24 25 26 31 32 33 34 35 36 41 42 43 44 45 46 51 52 53 54 55 56 61 62 63 64 64 66

Example: a character with Skill 3 and Stat 9 is attempting a Difficult task. The BTN is 26. He adds 9 for the skill (3*3=9) + 2 for the above-average stat (9-7=2), for a total modifier of +11. The result is not 37, as it would be in base-10. Instead, he counts 11 steps up the matrix; so the actual target number is 45.

To save time, Difficult-task TNs for all skills can be pre-calculated by the players before play begins. Adjusting for other Difficulty Levels is a simple matter of altering the first digit of the target number.

For tests of 0-level Default Skills, don't halve the characteristic (as in T4). Instead, increase the Difficulty by one level (by simply subtracting 1 from the first digit of the base target number).

As always, a roll of two sixes is a Spectacular Failure, and two ones is a Spectacular Success - even if the target number is below 11. Chance of Spectacular Success or Failure is always 2.8%.

NOTE: The T4 Multiple Actions rule will not work in this system. A new rule is needed: when attempting multiple actions, do not divide the characteristic. Instead, increase the difficulty two levels for each extra action (-2 to the first digit of the target number). Thus, for a character with stat of 7 and skill of 6, the target number for a single Difficult action is 56-; for two such actions, 36-; for three, 16-. (Obviously, this rule does not allow characters to perform as many extra actions as the original rule.)