Frozen_Feet
2013-07-24, 02:23 AM
This is a fairly generic system for stealth games, intended to be used with D&D Next, but can be easily adapted to any d20 system.
Stealth missions
Stealth mission refers to any attempt to move in, out or through an area while rousing minimal attention. While combat is not guaranteed to happen on a stealth mission, it shares some key traits with combat scenarios: namely, precise tracking of time, movement and locations of characters. While the operative time unit of stealth missions is usually closer to 1 minute than 1 round (=6 seconds), round-per-round processing of actions may be necessary when moving in close proximity of sentries.
Basics of Stealth
There are four basic states of hiddenness, modified by spells and special abilities. They are:
In Plain Sight: the character is not trying to hide. No check is required to spot him. If he steps within line of sight of any character, that character can notice him.
Sneaking: the character is trying to avoid attention while on the move, using shadows, camouflage or partial cover to mask his presence. Sneaking is usually conducted at just half the normal movement rate. The check DC to sneak is 5 points higher for the same conditions as hiding. Unaware characters do not notice the character.
Hiding: the character is trying to avoid attention by staying still in shadows or partial cover or while using camouflage. Hiding uses basic Stealth check DCs. Unaware characters do not notice the character.
Covered: the character is in total cover and a potential observer can't draw direct line of sight to him. Exact position of the character can't be known, but he can be indirectly detected unless hiding.
To successfully hide or sneak, a character must succeed in a Stealth check against DC based on the conditions he's in. To be able to make a check in the first place, he must be either:
In partial or total cover
Concealed by shadows, darkness, opaque mist, smoke or similar
In a crowd where there are at least 4 people in plain sight adjacent to him
Behind a character who is at least one size category larger
Wearing camouflage
The following conditions preclude making a stealth check:
Being in plain sight to any character you are trying to hide from
Carrying an open light source (such as a torch)
Being completely lit (without wearing camouflage)
Being completely lit and moving (even with camouflage)
The character does not have full knowledge of how well he is hiding or sneaking. He will only know for sure once he faces potential observers. This can be done in the following ways:
The GM tells the DC, but rolls for the character in secret.
The player rolls openly and knows his result, but doesn't get to know the exact DC.
The GM keeps both exact DC and result of the roll as secrets.
A failed check means the character is in plain sight. Once a character is succesfully hidden or sneaking, he will remain that way unless someone makes a succesfull search check to find him, or he is forced into conditions where sneaking and hiding are impossible (namely, bright light with no available cover). This means a succesfull sneak may remain unnoticed by unaware observers almost infinitely.
{table=head]Stealth Conditions | DC
Silenced and Invisible | 0
Silenced and in total cover | 5
Invisible | 5
In total cover | 10
In partial cover with camouflage | 10
Concealed with camouflage | 10
In partial cover | 15
Concealed (by shadow, smoke, mist etc.) | 15
In a crowd | 20
Wearing just camouflage | 20
Behind a larger creature | -5 per difference in size category
Sneaking | +5
Wearing conflicting colours (white against black etc.)* | +5
Wearing reflective items (bare steel etc.)* | +5
Moving at one-quarter speed** | -2
Wearing padded shoes*** | -2
Speaking with a whisper | +2
Speaking with normal voice | +5
[/table]
* Ignore if invisible.
** applies only when sneaking.
*** applies only when sneaking. Ignore this adjustment if silenced.
DC of 0 means the character can always hide succesfully. See "Stealth and special abilities" for further details on invisibility and silence. DC adjustments are cumulative.
Armor check penalty applies to stealth check made to sneak, but not to checks made to hide.
Basics of Observation
There are two basic senses almost all creatures use to spot intruders: sight and hearing. They may also have special sense as shown in their statistics - these will be dealt with later. Sight and hearing have defined ranges, varying from creature to creature. In bright light, sight has practically limitless range, but may be limited by obstacles (such as curvature of a planet). In twilight or darkness, it is sharply limited. The area which a creature can see is called its line of sight. Hearing is more limited, but is not always blocked by same obstacles as light. The area which a creature can listen to is called their hearing range.
In addition to a character's senses, whether it will detect an intruder depends on its state of alertness. There are four basic levels of alertness:
Unaware: the character is not specifically looking for anything, and is reliant on unsorted stimuli their senses pick up routinely. An unaware character will automatically spot characters in plain sight when they fall inside his line of sight, and will automatically hear noises as loud as or louder than normal speech. Unaware characters will not search for sneaking or hiding characters.
Alert: the character is not looking for any specific sneaking or hiding character, but is maintaining a constant vigilance of his surroundings. This is mentally taxing, so a character can only stay alert for a number of minutes equal to his Wisdom score, before his attention lapses and he becomes unaware for 1 minute minimum. An alert character will not search for hidden characters, but is entitled to make a Perception check when a sneaking character first passes through their line of sight or when a sneaking or covered (but not hiding) character first comes within hearing range. In the first case (sight), a succesfull check means the sneaking character's cover is blown, and he is now in plain sight. In the second case, the sneaking or covered character remains hidden, but the alert character becomes aware.
On patrol: as Alert, but the character has standing orders to periodically search certain places. The character will automatically search obvious hiding spots (behind doors, under beds, unlocked rooms), as detailed in his orders, whether anyone is actually hiding them or not.
Aware: this character knows something is amiss and is actively looking for an intruder. He is automatically entitled to a Perception check first time a sneaking or hiding character comes within his line of sight. If the check is succesfull, the intruder is found and is now in plain sight. He is also automatically entitled to Perception check first time a sneaking or hiding character comes within his hearing range. A heard intruder is still hidden, but the aware character can us Perception to approximate the area they're in. As usual, to make a Perception check to find a covered character, the aware character must move so he has line of sight to the intruder. If the initial free checks to spot the sneak fail, the aware character can keep searching but uses the normal searching rules from thereon. If the intruder succesfully slips away from both the aware character's line of sight and hearing range, the aware character will drop to either Alert or On patrol after a number of minutes equal to his wisdom score.
Characters will only move up in categories if they have a reason to. Unaware characters will only become Alert if they expect danger or tense situations. Alert character only become Patrolling characters if given orders by a convincing authority. Alert and Patrolling characters only become Aware if they spot or hear an intruder, if an alarm is sounded, or if they find compelling evidence of intruders being present. Compelling evidence could include (but is not limited to):
dirt or bloody footprints
broken accessories
missing valuables
dead bodies
Basics of Spotting and Searching
Spotting and Searching use the Perception skill. As detailed above, only Alert, Aware and patrolling characters are entitled to make the checks for spotting. Spotting uses the same DCs as searching. Searching is a more deliberate, time-consuming effort. Every 5' square takes 1 round (=6 seconds) to search if the DC to find a hidden character or object is 15 or less, and 1 minute if the DC is above that. Just like an intruder doesn't know how stealthy he is, searchers and spotters do not know how well exactly they have looked. Multiple attempts are of course possible, but cost time.
{table=head] Pereception Conditions (sight) | DC
Target is lit and moving | -
Target is lit but in a light crowd + | 0
Target is lit but in a moderate crowd + | 5
Target is lit but in a thick crowd + | 10
Target is lit but wearing camouflage* | 5
The target is hiding in light shadows, smoke or mist | 10
The target is hiding in heavy shadows (night), smoke or mist | 15
The target is hiding in pitch-blackness (enclosed room) | 20
The target is wearing camouflage* | +5
The target is in partial or total cover** | +5
The target is in a crowd of larger people | +5 per difference in size category
The target is sneaking | -5
The target is invisible | +10
The target is bleeding, dripping wet, covered in chalk etc. | -5
The target is on an easily imprinted surface (snow etc.) | -5
The target is wearing conflicting colours (white against black etc.)* | -5
The target is wearing reflective surfaces (bare steel etc.)* | -5
Character is moving with a crowd ++ | +5
Character is moving against a crowd ++ | -5
[/table]
+ in a light crow there are 1 to 10 people between the observer and the target. In a moderate crowd, there are 11 to 25 people between them. In a thick crowd, there are 26+.
++ don't apply normal modifier for sneaking target
* ignore if the target is invisible
** targets in total cover are not eligible for being spotted outright. Targets in total cover must be searched for in a time-consuming manner.
{table=head]Perception Conditions (hearing) | DC
Target is moving on a rough surface (loose gravel, creaky floorboards etc.) | 5
Target is moving on a hard surface | 10
Target is moving on a soft surface (heavy mattress etc.) | 15
Target is still | 20
Target is still and in total cover | 25
Target is still and in a sound-proof container | 30
Target is wearing padded shoes | +2
Target is whispering | -2
Target is speaking in a normal voice | -5
Target is shouting or casting a spell | -10
Target is silenced | +10
[/table]
DC of - means the target is in plain sight. Even unaware characters notice him with no check.
DC of 0 means unaware characters keep ignoring the target, but alert, aware and patrolling characters automatically spot him. Unaware characters only need someone to point out the presence of the target to notice him.
If the perception check is succesful and the hiding/sneaking character is within line of sight of the observer, the sneak's cover is blown and he is now in plain sight. If the sneak is not in line of sight, but is withing hearing range, the sneak remains hidden but the observer can now make additional search checks to find him. First succesful perception check to hear a hiding/sneaking target will reveal which 10' by 10' area they're in, or which direction they are moving towards. A second succesful perception check to hear a hiding/sneaking character will reveal which 5' by 5' square they're in.
Stealth missions
Stealth mission refers to any attempt to move in, out or through an area while rousing minimal attention. While combat is not guaranteed to happen on a stealth mission, it shares some key traits with combat scenarios: namely, precise tracking of time, movement and locations of characters. While the operative time unit of stealth missions is usually closer to 1 minute than 1 round (=6 seconds), round-per-round processing of actions may be necessary when moving in close proximity of sentries.
Basics of Stealth
There are four basic states of hiddenness, modified by spells and special abilities. They are:
In Plain Sight: the character is not trying to hide. No check is required to spot him. If he steps within line of sight of any character, that character can notice him.
Sneaking: the character is trying to avoid attention while on the move, using shadows, camouflage or partial cover to mask his presence. Sneaking is usually conducted at just half the normal movement rate. The check DC to sneak is 5 points higher for the same conditions as hiding. Unaware characters do not notice the character.
Hiding: the character is trying to avoid attention by staying still in shadows or partial cover or while using camouflage. Hiding uses basic Stealth check DCs. Unaware characters do not notice the character.
Covered: the character is in total cover and a potential observer can't draw direct line of sight to him. Exact position of the character can't be known, but he can be indirectly detected unless hiding.
To successfully hide or sneak, a character must succeed in a Stealth check against DC based on the conditions he's in. To be able to make a check in the first place, he must be either:
In partial or total cover
Concealed by shadows, darkness, opaque mist, smoke or similar
In a crowd where there are at least 4 people in plain sight adjacent to him
Behind a character who is at least one size category larger
Wearing camouflage
The following conditions preclude making a stealth check:
Being in plain sight to any character you are trying to hide from
Carrying an open light source (such as a torch)
Being completely lit (without wearing camouflage)
Being completely lit and moving (even with camouflage)
The character does not have full knowledge of how well he is hiding or sneaking. He will only know for sure once he faces potential observers. This can be done in the following ways:
The GM tells the DC, but rolls for the character in secret.
The player rolls openly and knows his result, but doesn't get to know the exact DC.
The GM keeps both exact DC and result of the roll as secrets.
A failed check means the character is in plain sight. Once a character is succesfully hidden or sneaking, he will remain that way unless someone makes a succesfull search check to find him, or he is forced into conditions where sneaking and hiding are impossible (namely, bright light with no available cover). This means a succesfull sneak may remain unnoticed by unaware observers almost infinitely.
{table=head]Stealth Conditions | DC
Silenced and Invisible | 0
Silenced and in total cover | 5
Invisible | 5
In total cover | 10
In partial cover with camouflage | 10
Concealed with camouflage | 10
In partial cover | 15
Concealed (by shadow, smoke, mist etc.) | 15
In a crowd | 20
Wearing just camouflage | 20
Behind a larger creature | -5 per difference in size category
Sneaking | +5
Wearing conflicting colours (white against black etc.)* | +5
Wearing reflective items (bare steel etc.)* | +5
Moving at one-quarter speed** | -2
Wearing padded shoes*** | -2
Speaking with a whisper | +2
Speaking with normal voice | +5
[/table]
* Ignore if invisible.
** applies only when sneaking.
*** applies only when sneaking. Ignore this adjustment if silenced.
DC of 0 means the character can always hide succesfully. See "Stealth and special abilities" for further details on invisibility and silence. DC adjustments are cumulative.
Armor check penalty applies to stealth check made to sneak, but not to checks made to hide.
Basics of Observation
There are two basic senses almost all creatures use to spot intruders: sight and hearing. They may also have special sense as shown in their statistics - these will be dealt with later. Sight and hearing have defined ranges, varying from creature to creature. In bright light, sight has practically limitless range, but may be limited by obstacles (such as curvature of a planet). In twilight or darkness, it is sharply limited. The area which a creature can see is called its line of sight. Hearing is more limited, but is not always blocked by same obstacles as light. The area which a creature can listen to is called their hearing range.
In addition to a character's senses, whether it will detect an intruder depends on its state of alertness. There are four basic levels of alertness:
Unaware: the character is not specifically looking for anything, and is reliant on unsorted stimuli their senses pick up routinely. An unaware character will automatically spot characters in plain sight when they fall inside his line of sight, and will automatically hear noises as loud as or louder than normal speech. Unaware characters will not search for sneaking or hiding characters.
Alert: the character is not looking for any specific sneaking or hiding character, but is maintaining a constant vigilance of his surroundings. This is mentally taxing, so a character can only stay alert for a number of minutes equal to his Wisdom score, before his attention lapses and he becomes unaware for 1 minute minimum. An alert character will not search for hidden characters, but is entitled to make a Perception check when a sneaking character first passes through their line of sight or when a sneaking or covered (but not hiding) character first comes within hearing range. In the first case (sight), a succesfull check means the sneaking character's cover is blown, and he is now in plain sight. In the second case, the sneaking or covered character remains hidden, but the alert character becomes aware.
On patrol: as Alert, but the character has standing orders to periodically search certain places. The character will automatically search obvious hiding spots (behind doors, under beds, unlocked rooms), as detailed in his orders, whether anyone is actually hiding them or not.
Aware: this character knows something is amiss and is actively looking for an intruder. He is automatically entitled to a Perception check first time a sneaking or hiding character comes within his line of sight. If the check is succesfull, the intruder is found and is now in plain sight. He is also automatically entitled to Perception check first time a sneaking or hiding character comes within his hearing range. A heard intruder is still hidden, but the aware character can us Perception to approximate the area they're in. As usual, to make a Perception check to find a covered character, the aware character must move so he has line of sight to the intruder. If the initial free checks to spot the sneak fail, the aware character can keep searching but uses the normal searching rules from thereon. If the intruder succesfully slips away from both the aware character's line of sight and hearing range, the aware character will drop to either Alert or On patrol after a number of minutes equal to his wisdom score.
Characters will only move up in categories if they have a reason to. Unaware characters will only become Alert if they expect danger or tense situations. Alert character only become Patrolling characters if given orders by a convincing authority. Alert and Patrolling characters only become Aware if they spot or hear an intruder, if an alarm is sounded, or if they find compelling evidence of intruders being present. Compelling evidence could include (but is not limited to):
dirt or bloody footprints
broken accessories
missing valuables
dead bodies
Basics of Spotting and Searching
Spotting and Searching use the Perception skill. As detailed above, only Alert, Aware and patrolling characters are entitled to make the checks for spotting. Spotting uses the same DCs as searching. Searching is a more deliberate, time-consuming effort. Every 5' square takes 1 round (=6 seconds) to search if the DC to find a hidden character or object is 15 or less, and 1 minute if the DC is above that. Just like an intruder doesn't know how stealthy he is, searchers and spotters do not know how well exactly they have looked. Multiple attempts are of course possible, but cost time.
{table=head] Pereception Conditions (sight) | DC
Target is lit and moving | -
Target is lit but in a light crowd + | 0
Target is lit but in a moderate crowd + | 5
Target is lit but in a thick crowd + | 10
Target is lit but wearing camouflage* | 5
The target is hiding in light shadows, smoke or mist | 10
The target is hiding in heavy shadows (night), smoke or mist | 15
The target is hiding in pitch-blackness (enclosed room) | 20
The target is wearing camouflage* | +5
The target is in partial or total cover** | +5
The target is in a crowd of larger people | +5 per difference in size category
The target is sneaking | -5
The target is invisible | +10
The target is bleeding, dripping wet, covered in chalk etc. | -5
The target is on an easily imprinted surface (snow etc.) | -5
The target is wearing conflicting colours (white against black etc.)* | -5
The target is wearing reflective surfaces (bare steel etc.)* | -5
Character is moving with a crowd ++ | +5
Character is moving against a crowd ++ | -5
[/table]
+ in a light crow there are 1 to 10 people between the observer and the target. In a moderate crowd, there are 11 to 25 people between them. In a thick crowd, there are 26+.
++ don't apply normal modifier for sneaking target
* ignore if the target is invisible
** targets in total cover are not eligible for being spotted outright. Targets in total cover must be searched for in a time-consuming manner.
{table=head]Perception Conditions (hearing) | DC
Target is moving on a rough surface (loose gravel, creaky floorboards etc.) | 5
Target is moving on a hard surface | 10
Target is moving on a soft surface (heavy mattress etc.) | 15
Target is still | 20
Target is still and in total cover | 25
Target is still and in a sound-proof container | 30
Target is wearing padded shoes | +2
Target is whispering | -2
Target is speaking in a normal voice | -5
Target is shouting or casting a spell | -10
Target is silenced | +10
[/table]
DC of - means the target is in plain sight. Even unaware characters notice him with no check.
DC of 0 means unaware characters keep ignoring the target, but alert, aware and patrolling characters automatically spot him. Unaware characters only need someone to point out the presence of the target to notice him.
If the perception check is succesful and the hiding/sneaking character is within line of sight of the observer, the sneak's cover is blown and he is now in plain sight. If the sneak is not in line of sight, but is withing hearing range, the sneak remains hidden but the observer can now make additional search checks to find him. First succesful perception check to hear a hiding/sneaking target will reveal which 10' by 10' area they're in, or which direction they are moving towards. A second succesful perception check to hear a hiding/sneaking character will reveal which 5' by 5' square they're in.