Roleplayer #22, November 1990
Cthulhu Lives!
Lovecraftian Horror in GURPS
By David Ellis Dickerson
All those vile Ayshuns of Khopee rites aside, there are many people who
like the GURPS
Horror system, and would like to do some Lovecraftian
adventuring with their characters. The only problem is that GURPS
cannot produce any "official" Lovecraft material because Chaosium
owns the rights. Chaosium has put out a lot of wonderful Cthulhoid adventures,
but there will never be similar adventures written just for GURPS
Horror.
But why should this stop the determined gamer? The Rules Police don't visit
private parties, and there's nothing to stop you from buying a CoC
module and running it with GURPS characters --
nothing, that is, except the differences between the systems. How can you
lose Sanity if you don't have it (as a characteristic) in the first place?
How can you cast spells if you don't have any Magic Points? And how does
a CoC skill like Credit Rating transfer to GURPS?
Don't worry. The two systems are remarkably similar when it comes right
down to it, and with just a little word-juggling, you'll be ready to hunt
down the Fungi from Yuggoth, whether you have the Call of Cthulhu
rules or not.
Characteristics
There are a lot of characteristics in Call of Cthulhu,
and some of them -- such as Power -- have many uses, but don't translate
between Systems very seamlessly. Here are the basics:
If you're translating investigators, subtract 2 from INT to determine GURPS
IQ. Investigators tend to start with extremely high INT, which
costs more than an average 145-point character can afford.
Use the CoC Appearance characteristic (APP) to
find the character's Appearance in GURPS:
CoC Appearance.....GURPS Appearance
3-4...................Hideous (-4)
5-6...................Ugly (-2)
7-8...................Unattractive (-1)
9-12..................Average
13-14.................Attractive (+1)
15-16.................Handsome/Beautiful (+2/+4)
17-18.................Very Handsome/Beautiful(+2/+6)
A character's CoC Power is equal
to GURPS Will, so compare Power
with Intelligence, and modify it up or down with Strong Will or Weak Will,
in order to achieve the correct score. (Example: A CoC
character has INT of 13 and POW of 10. In GURPS,
he has IQ 13 and -3 Weak Will.)
Power also determines GURPS Magical Aptitude.
Power of 12-14 gives Magery 1; Power of 15-17 gives Magery 2, and Power
18-20 gives Magery 3.
In order to reflect the CoC rules, you may wish
to give characters with Power of 15 or better the Luck advantage (15 points).
30 points of Luck does not exist in any Lovecraft story!
Movement should be figured from GURPS characteristics.
Where the mode of movement is different (such as flying), translate the
number directly: CoC Move = GURPS
Move.
These rules are all right for the average investigator, but the monsters
-- particularly the tougher ones -- may have characteristics which go much
higher than normal. Here's how to deal with it.
High STR = High ST. Use the ST chart from GURPS
Supers to determine Thrust and Swing damage. (For your
convenience, this is reproduced at the end of this article.)
High CON = Give the creature HT 20, and as many hits as are listed under
Hit Points after a slash, just as is done for animals. (Example: Zhar the
Twin Obscenity has 100 CON and 100 Hit Points. In GURPS,
he has HT 20/100.)
High SIZ = Any monster with SIZ of 35 or more has advantages for being larger.
Divide SIZ by 20, and round off. This is how many full 100% increases in
Growth (from GURPS Supers) the being has. For
those without Supers, every time height doubles,
ST doubles, Hits double, and Weight goes up eight times, while Move when
walking or swimming (only) increases by 50%. However, you can assume that
the creature stats as they are given in CoC (such
as Hits, STR, and Move) already reflect the growth of the creature they
describe.
Some beings (e.g., the Insects from Shaggai and the Fire Vampires) have
SIZ of 1. Treat them as swarms (B143) with the given hits and doing the
described damage.
High INT = INT higher than 20 is either IQ 20 or IQ (INT/2), whichever is
higher.
High POW = For every full 10 levels of Power above 20, give the creature
another level of Magic Aptitude. (So 30-39 gets +4, 40-49 gets +5, etc.)
Aside from this, most creatures have enough Fatigue from their increased
ST to fuel their Magic. In the rare case that a being's POW exceeds its
ST, use the POW rating as if it were extra Fatigue, bought for spell-casting
purposes. (This costs S character points per point of Fatigue; see GURPS
Supers, p.20).
Damage = Use the creature's ST. Tentacles and appendages do swing/crushing
damage. Bites do thrust/cutt-ing damage (for regular teeth) or thrust/impaling
damage (for fangs). Claws and pincers do swing/cutting, and spines and horns
do thrust/impaling. Use weapons as they are described in the Weapons Chart.
All other attacks (including blood drain, teleport, engulf, and so on) are
considered Special; just take damage straight from CoC.
CoC armor, by the way, is exactly the same as
GURPS DR. Cthuloids have the
same Passive Defense as a GURPS creature with
equivalent hide.
Skills
Many skills have exactly the same name in the two systems. Unfortunately,
CoC operates on a percentile rather than a three-die
system.
While it's tempting to take the skill percentages and translate them into
die rolls (based on the chart on B45), don't do it. Most investigators have
terribly low success chances with their skills, and your translated investigators
(who are professionals, remember) will have most of their skills at rolls
of about 8 to 10 (25% to 50%). Instead, consider any skill of 50% to have
been bought at IQ or DX level. For every full ten points above or below
50% (which means 45% and 55% are considered 50%), reduce or increase the
IQ or DX roll by one.
Example: Festus Curtis, private eye, is a Call of Cthulhu
character with INT 14, DEX 11, Handgun Attack 50%, Psychology 35%, Driving
20% and Latin 75%. In GURPS Horror, he'll have
IQ 14, DX 11, and Guns (Pis-tol)-13 (bought at DX level, with a +2 IQ bonus),
Psy-chology-13 (IQ-1, since 35 is only one full multiple often below 50),
Driving (Automobile)-8 (at DX-3 level) and Latin-16 (IQ + 1, since 75 is
two full multiples often above 50).
As mentioned before, most skills have the same name (or at least very similar
ones) in both systems. Here are the exceptions:
Credit Rating, in CoC, is supposed to represent
impressive credentials and the ability to bluff through red tape. In GURPS,
this might be Social Status or Military Rank, or a good personal Reputation,
depending on the character background. Allow an appropriate status-type
advantage worth +1 on reaction for every full 10% above the original Credit
Rating score (15%). In addition, any character with Status of 3 or higher
automatically has Savoir-Faire at IQ level.
Cthulhu Mythos is a Mental/Very Hard skill. It is used to identify Mythos
creatures' involvement in a given scenario, and to identify particular creatures
by name. Use the following modifiers:
In addition, there are certain skills which are unavailable in CoC
which should be given to investigator characters. Journalists should get
Journalism at IQ level. Dilettantes should have Savoir-Faire. And the GM
should consider giving private investigators Shadowing, and police officers
Criminology or Forensics (at TL6, of course).
Sanity
CoC players lose Sanity under about the same conditions
that GURPS players make Fright Checks. The more
potential Sanity loss, the harder the Fright Check. To figure the exact
penalty, total up the maximum Sanity loss possible. (GURPS
characters don't get Will rolls to avoid Sanity loss, so if there's a listing
such as 1d6/1 point, it means 6 possible Sanity.) Divide this number by
two, and round down. This will give you the Fright Check penalty.
Example: An adventure states that reading a given book will invite 2D8 Sanity
loss. The maximum Sanity loss from a roll of 2D8 is 16. Divide this in half,
and you can tell any GURPS Horror players who
read the book that they must make a Fright Check at -8. (Exception: seeing
one of the Outer Gods usually invites 1D100 Sanity loss! Treat this as a
Fright Check -20.)
Magic
You may use spells from either Call of Cthulhu
or GURPS. Magic Point cost is the same as Fatigue
cost, and damage translates exactly: 1D10 hit points' damage is 1D10 HT
damage. You may change all "1D10" references to "2d-1,"
and all "1D8"s to "1d+1"s, but the point is that damage
is lost at the same rate in both systems. Any spell which costs more than
12 Magic Points/Fatigue is as a Very Hard skill.
Monstrous Strength
Here's the strength chart (from Supers p.79) for
strengths higher than 20:
ST.....Thrust...Swing.....ST.....Thrust...Swing
21.......2d........4d-1.......45........5d.......7d+1
22.......2d.........4d........50.......5d+2......8d-1
23......2d+1.......4d+1.......55........6d.......8d+1
24......2d+1.......4d+2.......60.......7d-1.......9d
25......2d+2.......5d-1.......65.......7d+1......9d+2
26......2d+2........5d........70........8d........10d
27......3d-1.......5d+1 ......75.......8d+2......10d+2
28......3d-1.......5d+1.......80........9d........11d
29.......3d........5d+2.......85.......9d+2......11d+2
30.......3d........5d+2.......90........10d.......12d
31......3d+1.......6d-1.......95.......10d+2.....12d+2
32......3d+1.......6d-1.......100.......11d.......13d
33......3d+2........6d........110.......12d.......14d
34......3d+2........6d........120.......13d.......15d
35......4d-1.......6d+1
36......4d-1.......6d+1
37.......4d........6d+2
38.......4d........6d+2
39......4d+1.......7d-1
40......4d+1.......7d-1
and so on: +1d for each full 10 points of added ST.
And that should about do it. Using these rules, you can translate characteristics,
skills, monsters, magic spells, and even insanity. In fact, about the only
thing you can't do is beat the bad guys. But that's Lovecraft for you. Isn't
it nice to have him in your campaign?
Our thanks to Chaosium for granting their permission to publish this
article. Call of Cthulhu and its supplements are copyrighted
by Chaosium, Inc., and Call of Cthulhu is a registered
trademark of Chaosium.
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