Steve Jackson Games - Site Navigation
Home General Info Follow Us Search Illuminator Store Forums What's New Other Games Ogre GURPS Munchkin Our Games: Home

Go Back   Steve Jackson Games Forums > Roleplaying > The Fantasy Trip > The Fantasy Trip: House Rules

Reply
 
Thread Tools Display Modes
Old 09-07-2018, 10:36 AM   #1
flankspeed
 
Join Date: Jul 2018
Default Perception Rolls (Including Non-Humanoid Creatures)

Perception Rolls

Here are some house rules for Perception Rolls, including those made by non-humanoid creatures. The rules begin by assuming it is unusual for a figure to spontaneously notice something hidden or hard to detect by the senses. Without a high IQ or some positive modifiers to the situation, detection will only happen by pure luck.

A figure passively perceiving its surroundings with average senses, under normal environmental conditions, would identify a target difficult to perceive only on a successful Perception Roll of 4d vs IQ, subject to the following cumulative modifiers.


Base Perception Roll when figure is unaware: 4d vs IQ

-- The Alertness talent qualifies the figure as always actively searching its surroundings, giving a -1d bonus modifier. It is impossible to combine active searching with Alertness because the talent means you are already searching all the time.

-- The Detect Traps talent qualifies the figure as always actively searching for traps and nothing else, but this focus gives a -2d bonus modifier to find traps instead of the usual -1d for actively searching. Alertness plus Detect Traps offers no cumulative benefit to trap detection, but Alertness does still function to detect other things if a figure possesses both talents. It is impossible to combine actively searching for traps with Detect Traps because the talent means you are already searching for traps all the time.

-- Figure is actively searching its surroundings: -1d

-- Figure is performing actions that distract from situational awareness: +1d

-- Figure has acute or heightened senses above normal: -1d

-- Figure has dull or diminished senses less than normal: +1d

-- Target is very badly camouflaged/hidden: -1d

-- Target is excellently camouflaged/hidden: +1d (more for expert traps)

-- Target doesn’t have Silent Movement and fails Stealth Roll: -1d

-- Target doesn’t have Silent Movement but makes Stealth Roll: +0d

-- Target has Silent Movement but fails Stealth Roll: +0d

-- Target has Silent Movement and Makes Stealth Roll: +1d

-- Environmental factors enhancing detection: -1d per factor

-- Environmental factors hindering detection: +1d per factor


A Perception Roll reduced to 1d vs IQ or less is an automatic success. Silent Movement refers to the Silent Movement talent. A Stealth Roll is 3d vs DX that must be rolled by the target trying to move stealthily BEFORE the Perception Roll is made.

A 16, 17, or 18 on a Stealth Roll always reveals the target attempting to move quietly even if it has Silent Movement. No Perception Roll is needed. And a 16, 17, or 18 on a Perception Roll always fails to spot its target.

These rules mean that an average human unaware of danger would spot an average ambush -- made by attackers who do not have Silent Movement but who made their Stealth Rolls -- only on a successful roll of 4d vs IQ. The only modifier would be +0d for the attackers making their Stealth Rolls.

Possessing keen senses, such as the Acute Hearing talent, would reduce this Perception Roll to 3d vs IQ despite the figure being unaware of danger. A figure without Acute Hearing who is actively looking for an ambush would also succeed on 3d vs IQ. And a figure actively searching with Acute Hearing would need to succeed on a roll of only 2d vs IQ.



Non-Humanoid Creatures

Most non-humanoid creatures have intelligence ranked on the animal scale rather than the human scale, with a typical IQ of 0 to 7. Such creatures make base Perception Rolls as defined above by rolling against IQ plus a proficiency modifier based on age.

For very young creatures, roll 1d; for adolescents, roll 1d+2; and for adult creatures, roll 1d+4. (Alternatively, an average value of 7 for an adult could simply be used, or the GM may assign an appropriate number.)

This proficiency modifier results in a Perception Roll against a number ranging from IQ+1 to IQ+10, reflecting the difference between individual creatures. The difference can be explained by age, disease, injury, experience, and sensory acuity. The proficiency modifier normally remains the same once determined, but the GM could modify it over time, such as due to aging or when player characters train pets or mounts.

If the creature is carnivorous and hunts for its food alone or in packs, is descended from predatory ancestors, or is regularly hunted as prey by predators, then treat most of these creatures as possessing acute senses qualifying for a -1d Perception Roll bonus. Truly exceptional creatures may actually possess the Alertness talent, though this should be uncommon since even a sharp-listening dog benefits from perking up its ears in an active search rather than listening passively.

It may be easier to bring a pet along than to learn Acute Hearing or Alertness. After all, there are good reasons why people use guard dogs.

If a creature needs to detect a threat and the senses it relies on are hindered in some way (such as sight by darkness, night vision by bright light, smell by wind direction, or hearing by noise), then the creature’s Perception Roll is subject to as many +1d environmental factor penalties as apply.

It is common for predatory creatures to possess Silent Movement, as will some smaller prey animals. When individual prey animals in a herd are feeding or drinking, they may qualify for the +1d distracted from situational awareness penalty, but the benefit of congregating together is that some of the herd will actively look for danger while others graze.


NOTE: As always, feel free to modify these rules for personal use!
__________________
"What you don't know can't hurt y ... OUCH!"

Last edited by flankspeed; 09-09-2018 at 11:21 PM.
flankspeed is offline   Reply With Quote
Reply

Tags
detection, hiding, perception, searching, stealth

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Fnords are Off
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 04:03 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2020, vBulletin Solutions, Inc.