GURPS101: Deconstructing Detect

Detect is one of those advantages in GURPS that can be used for a multitude of things. It can be used for strange alien races that can “hear” radio, telepaths who can sense other minds, and many other things.

So how does Detect break down?

Detect as Pieces Parts
So exactly what does this trait do and how does it do it?

  • You can detect a specific substance or condition.
  • You do not rely on the standard five human senses to do so and gain a “sixth sense” to find substances or conditions.
  • This requires that you concentrate and is not consider a passive ability.
  • You use the standard range modifiers (p. B550).
  • You can discern what you’ve perceived with a follow-up IQ roll.
  • Detect’s cost is based on the rarity of what is detected. This may change depending on the campaign setting, but p. B48 lists a “common” set occurrences.
  • You may purchase an Acute Sense (p. B35) for it if you wish.

Canon Detect Special Modifiers

Detect has several special modifiers, but there are also a few general modifiers that are useful: Reflexive (GURPS Powers, p, 109) turns Detect into a passive sense; Short-Range and Long-Range (GURPS Powers, p, 112 or 108) modify the distance; Melee Attack (p. B112) can make it a “touch-range” sense; Sense-Based, Reversed (GURPS Powers, p. 00) allows the detect to function through your senses instead of becoming a “sixth sense.”

  • Analyzing (Enhancement; GURPS Powers, p. 49): Your advantage analyses what you sense.
  • Analysis Only (Limitation; GURPS Psionic Powers, p. 14): Your advantage relies on your mundane senses to locate.
  • Cannot Analyse  (Limitation; GURPS Psionic Powers, p. 14): Your advantage allows you to detect, but not analyze what you locate.
  • Hypersensory (Limitation; GURPS Powers: Enhanced Senses p. 8-9): Your advantage uses your mundane senses to locate and analyse.
  • Precise (Enhancement; GURPS Basic Set, p. 48): Your advantage can locate the position of whatever you detect.
  • Precise, Nontargeting (Enhancement; GURPS Psionic Powers, p. 14): As for precise, but you cannot use follow-up abilities.
  • Restricted Arc (Limitation; GURPS Powers: Enhanced Senses p. 9): Your advantage isn’t 360.
  • Signal Detection (Enhancement; GURPS Basic Set, p. 48): Your advantage allows you to detect active transmissions only.
  • Stethoscopic (Limitation; GURPS Powers: Enhanced Senses p. 9): Your advantage works through walls, surfaces, etc.
  • Vague (Limitation; GURPS Basic Set, p. 48): Your advantage only detects the presence or absence of something.

New Variation of Detect: Esoteric Detect
A new spin on an old trait.


p. B48

The following is a variation of Detect which allows the location of a idea, concept, or other ephemeral condition.

Esoteric: Your Detect works as written, but what you locate is something like “Death” or “Lust.” This allows you to find and analyse such these things normally, but you can also find echoes of them: To do this use the standard range table (p. B550), and look up your margin in the Size column. Next, read the Linear Measurement column and read yards as minutes. This is the distance you can locate things into the past. For example, if you succeeded your roll by 5 then you could detect things up to 155 minutes in the past. You can still analyze what you locate, but you must be in its presence as it’s occurring or has occurred – reading “echoes” inflicts a -5 penalty.

Special Modifiers
Long-Range: Each level of this modifier shifts the time you can detect things in the past one step favorably: read “minutes” as “hours,” “hours” as “days,” “days” as “weeks,” “weeks” as “months” and “months” as “years.” +50%/level.
Sensitive: You pick up echoes much easier than others – ignore the -5 penalty. +20%.
Short-Range: Each level of this modifier shifts the time you can detect things in the past one step less favorably: read “minutes” as “seconds.” Further levels halve the final time ad infinitum. -10%/level.

Example Build: Death-Sense
A sixth sense allowing you to sense death, the dead, and the dying in your vicinity.

Death-Sense: Detect Death (PM, -10%) [18]. Make an IQ roll to detect the dead, dying, or immediate death of those in your location; add the standard range penalties. You may also detect the past “echoes” of such things. In that case, make an IQ roll at -5 and look up your margin in the Size column of the Size and Speed/Range Table. Next, read the Linear Measurement column and read yards as the number of minutes you can read an echo.

Powering It Up:

  • For 4 points you can ignore the -5 penalty for reading echoes.
  • For 10 points you can read “minutes” as “hours” when reading echoes; additional levels cost a further 10 points each and let you read read “hours” as “days,” “days” as “weeks,” “weeks” as “months” and “months” as “years.”
  • For 20 points you can automatically analyse whatever you are detecting.
  • For 4 points you can exclude known sources of death.
  • For 20 points you can pinpoint a specific instance of death.
  • For 8 points your ability becomes a passive sense allowing you to use it automatically.


Picking Over the Bones
There are several posts on the Steve Jackson Games forums that might be useful. I know that I’ve drawn on them over the years. I had to effectively invent the Esoteric Detect variation for my own games after I realized the standard Detect didn’t do what I wanted it to do. Overall, I hope these little posts are useful to my readers.

Do you have any custom modifiers you use for Detect in your games? Any instances where Detect has been pivotal to your games or character?

Posted in GURPS 101 and tagged , , .

One Comment

  1. Pingback: GURPSDay Summary Dec 7, 2018 – Dec 13, 2018 - Gaming Ballistic

Leave a Reply