[Design] Why random rolls?

[Lev Lafayette]

--- Kyle Schuant <kyle3054 at iprimus.com.au> wrote:

> From: Lev Lafayette 
> I may also make mention of Karl's d4-d4 system where
> the random effects to the base roll can be positive
> or
> negative. That's really a nice touch.
> ***
> 
> I think you mean, "Kyle's d4-d4 system.":)

Er yes. I'm not dyslexic, honestly.


> LL: Anyway here's an initial proposition within the
> game
> design.
> 
> KS: I couldn't follow any of that. I think you need
> to illustrate it with examples. Actual numbers.

OK, the idea is pretty simple. The basic principle is
the degree of randomness varies according to the
action performed.

Most games do this to an extent. Calculated abilities
versus skills for example.

In GURPS, your basic move is (HT+DX)/4. Such an action
has no random influence. Your ability to hit a target
with a bow, for example, is influenced by random
factors; so you roll 3d6 and try to achieve under your
skill.

Now my point is that these are "all or nothing"
propositions. In GURPS (and almost every other system
under the sun), the degree of randomness is either
absent or applied. There is no sense of a range of
randomness.

OK, here's the alternative (straight from the rules).

6) Skill Randomness

Depending on the type of activity or their relative
importance of the incident to the story, different
skills will have a different influence of randomness
in determining the Trait Effect. In some cases, such
as where skill has a minimal influence on a Trait or
the incidence is trivial to the plot, an effect can be
calculated directly from the Trait score plus any
additional modifiers (e.g., walking rate in metres per
second). In the majority of cases however, successful
skill use will provide from a minor bonus or penalty
to Trait effects to a significant one. The more basic
the skill is, the less it is influenced by random
factors.

In general there are four categories of skill results;
a critical (equal to or less than 1/10th of the skill
value - drop fractions), a success, failure, and a
fumble (equal to one tenth or more of  the failure
range, likewise drop fractions). Likewise there are
four degrees of random influence on generating effect
scores; none, tiny, small, medium, large.

Where the degree of randomness is 'none', simply apply
the final effect as described. There is no need to
roll against the skill. Indeed, the skill rating
usually determines the modifier. See the individual
skill descriptions for an explanation.

(e.g., The basic rate of movement for a character in
metres per second is their (Str+Agi)/4)

Where the degree of randomness is 'tiny', a critical
means the final effect is multiplied by 1.2, a success
by 1.0, a failure by 0.8 and a fumble by 0. This is
typically used for trait-derived actions where the
character is making special effort) (e.g., running a
race, weightlifting etc).

(e.g., A character makes special effort at jumping
using their Athletics skill. They roll a critical!
Their jump is increased by 20% from the derived value)

Where the degree of randomness is 'small', a critical
means that the final effect is multiplied by 1.5, a
success is multiplied by 1.0, a failure by 0.5, and a
fumble by 0. This is typically used for basic skills
under stressful situations.

(e.g., A character attempts to scan an area. They fail
their roll. Their perception is 15, they roll 3d6 for
the effect value and halve the result).

Where the degree of randomness is 'medium', a critical
means the final effect is multiplied by 2.0, a success
by 1.0, a failure by 0, and a fumble by -0.5. That is,
a negative effect roll is applied against the
character as some mishap or misfortune.

Where the degree of randomness is 'high', a critical
means the final effect is multiplied by 3.0, a success
by 1.0, a failure by 0, and a fumble by -1.0.


7) Effects Score

In nearly all circumstances, a character's trait
determines the range of Effect with every five points
in a Trait providing a 1d6 Trait bonus. Thus a
character with a Strength Trait of 10 will roll 2d6
for determining Trait effects. Every two point above
five provides a bonus of +1, every three and four
points a bonus of +2.

Use multiples for values over 20 (e.g., Strength 30 is
3 times 10 so 3*2d6). This scale increases in a linear
fashion every two points in both range and averages.

In the simple use of a Trait the effect score is
compared to a previously determined difficulty value
and the relative degree of success and failure can be
determined by comparison. In a simple competition the
two or more effect scores are compared against each
other and the relative degree of success or failure
can be determined by comparison.

(e.g., Burly Bob arm-wrestles Hakkim The Trader. Bob
has a Strength of 15, giving him 3d6 for determining
an effect score. Hakkim has a Strength of 8, giving
him 1d6+2. Bob's range is 3-18 with an average score
of 10-11. Hakkim has a range of 3-8 and an average
score of 5-7. Hakkim has a chance, but it isn't that
good)

A character's Spirit score may be used to give
temporary enhancement to a Trait in determining an
effect score. This is risky. Using a base difficulty
value of 10, determine a simple effect score based on
Spirit. For every three points the Spirit score
succeeds by, one's Trait is temporarily increased by
one point for purposes of the directed effort.
However, for every point the Spirit score fails, the
Trait is temporarily reduced by one point! Further,
such directed focus also means that the character is
unable to engage in any other actions whilst they are
making use of the bonus.

(e.g., Hakkim's chances aren't looking good at all.
But he does have a Spirit of 18! Burly Bob in contrast
has a mere score of 8 - he's big, but he's just not
that motivated. Hakkim decides to use his Spirit to
push up his Strength through force of will. His effect
score range is 5-27. He rolls a 20, making the roll by
10 and increasing his Strength by another 3 points up
to 11... OK, it's still not great, but looking a lot
better). 

Effect scores are also critical in physical and
psychic combat resolution. Refer to the appropriate
section (chapter V) for a detailed examination of
physical and psychic combat.



		
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