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 > GURPS

Reply
 
Thread Tools Display Modes
Old 03-23-2016, 08:57 AM   #81
Varyon
 
Join Date: Jun 2013
Default Re: Dodgin' Bullets

Having given this some thought, here are some ideas of how to handle the dodging of bullets and the like.

There are three ways to avoid a ranged attack. The first is to simply make yourself difficult to hit - this is Evasive Movement in one form or another, and should give an attack penalty.

The second is to get out of the way of others' attempts to draw a bead on you. For Aiming, use the rules from On Target (Pyramid #3/77), but allow for the target to Dodge the Aiming attempt (the target should also be able to try and shake the Aim off on their own turn). For an attack, simply use the default Dodge rules. Against Sighted Shooting (All-Out or Committed), however, in the case of a successful defense the attacker should probably get a roll to hold their fire, as they can tell they aren't going to hit.

The third is to perceive the projectile's path and get out of the way (or put something in the way). This uses the perception rules from Dodge This! (Pyramid #3/57), but apply a +10 to the check (don't apply this when determining if you can perceive it, however). On a success, check your MoS on the SSR table and see the distance that corresponds to that value - that is how far away the projectile is when you are able to react to it. Divide this distance by the projectile's speed in yards per second - this is how many seconds you have before the projectile reaches you. Multiply this number by 10 and read it as "yards" in the range column of the SSR table (rounding up as usual), and apply the corresponding SM value to the character's Active Defense. There is a hard limit here, based on the attacker's range and your own reaction speed (represented by unencumbered Dodge, with a further +9 for characters with ETS). You cannot* perceive the projectile from further away than where it originated, and you lose some time before actually being able to react to it. Determine how many seconds the projectile takes you reach you and subtract 0.2 from this for a character with Dodge 8 (every +1 to Dodge is -1 SSR to this value), then multiply by 10 and determine the corresponding bonus/penalty, as usual. This is the maximum bonus you can get. If it is 0 or lower, you are outright incapable of perceiving the projectile before it hits you, and thus cannot attempt such a defense (you can still Dodge the foe's aim, as above). Resolve the defense on the round the projectile would actually hit, for bullets that take a second or longer to strike. While cinematic, assume the bullet actually keeps heading toward the target, regardless of where they go**.

When defending against an attack, use whichever of the last two rules gives a higher bonus. Note Predictive Shooting does not penalize Dodges when using the perception rules. Similarly, you can only use the perception rules to avoid bombardment-style attacks (like Suppression Fire and the like). The above is for Dodges - Blocks and Parries should be a bit more difficult, but I'm not certain exactly what the relationship should be (doubling any penalty and halving any bonus is a good quick-and-dirty option).

Note this adds a lot of complication. Note also that we're kind of double-dipping with Dodge, as a character with a high Dodge has a higher absolute bonus. For example, let's say we've got someone firing a 600 y/s bullet from 200 yards away. The bullet takes 0.333 seconds to reach its target. A character with Dodge 8 cannot perceive it from closer than 0.133 seconds away, meaning he can't get better than Dodge -1 if basing his Dodge on perceiving the bullet. A character with Dodge 11, however, can perceive the bullet from up to 0.263 seconds away, allowing for a Dodge at +1. Give that Dodge 7 character ETS (boosting Dodge to 8, and Reaction Speed to 17) and he can perceive the bullet from 0.283 seconds away - good for a +1. Of course, the characters need to actually roll well enough on their Per checks to actually get these bonuses.


*This being GURPS, you'll need to adjust these rules for characters with precognition.

**Optionally, if the target moves at least 1 yard between the foe shooting the projectile and the projectile hitting, this replaces the Time of Flight modifier with a minimum roll. If a bullet would hit in 3 seconds (3d-15) but the target sees it at 2 seconds out, the roll becomes 1d-15+2. This is in addition to any applicable Dodge bonus.

Last edited by Varyon; 03-23-2016 at 10:34 AM. Reason: BS 5 means Dodge 8, not Dodge 7; numbers adjusted to account for this
Varyon is offline   Reply With Quote
Old 03-23-2016, 10:08 AM   #82
Ulzgoroth
 
Join Date: Jul 2008
Default Re: Dodgin' Bullets

Quote:
Originally Posted by Varyon View Post
There are three ways to avoid a ranged attack. The first is to simply make yourself difficult to hit - this is Evasive Movement in one form or another, and should give an attack penalty.
I want, again, to contest this.

Unless your attacker has a sufficiently superior theory of mind that they can anticipate your attempts at random movement, there's not actually anything skill can do to compensate for the unknowable component of your displacement. It behaves like Dodge, not like an attack penalty.
__________________
I don't know any 3e, so there is no chance that I am talking about 3e rules by accident.
Ulzgoroth is offline   Reply With Quote
Old 03-23-2016, 10:27 AM   #83
Varyon
 
Join Date: Jun 2013
Default Re: Dodgin' Bullets

Quote:
Originally Posted by Ulzgoroth View Post
I want, again, to contest this.

Unless your attacker has a sufficiently superior theory of mind that they can anticipate your attempts at random movement, there's not actually anything skill can do to compensate for the unknowable component of your displacement. It behaves like Dodge, not like an attack penalty.
Dodge requires you to know you're being shot at, degrades the more foes there are trying to attack you, and can be compensated for by sufficient skill anyway (via Predictive Shooting). A skill penalty is just a cleaner solution all around, IMO, although it's not going to really break anything if you have it as a modified Dodge instead.

Last edited by Varyon; 03-23-2016 at 10:33 AM.
Varyon is offline   Reply With Quote
Old 03-23-2016, 10:35 AM   #84
Ulzgoroth
 
Join Date: Jul 2008
Default Re: Dodgin' Bullets

Quote:
Originally Posted by Varyon View Post
Dodge requires you to know you're being shot at,
It shouldn't when you're dodging by general evasive movement. This is hardly a novel observation.
Quote:
Originally Posted by Varyon View Post
degrades the more foes there are trying to attack you,
Since when?
Quote:
Originally Posted by Varyon View Post
and can be compensated for by sufficient skill anyway (via Predictive Shooting).
That's really easy to fix.
Quote:
Originally Posted by Varyon View Post
A skill penalty is just a cleaner solution all around, IMO, although it's not going to really break anything if you have it as a Dodge instead.
A skill penalty only makes any sense when the travel time is too short to actually evade in so it's a matter of the attacker shaving their aimpoint response time so as not to get faked out.
__________________
I don't know any 3e, so there is no chance that I am talking about 3e rules by accident.
Ulzgoroth is offline   Reply With Quote
Old 03-23-2016, 10:50 AM   #85
Varyon
 
Join Date: Jun 2013
Default Re: Dodgin' Bullets

Quote:
Originally Posted by Ulzgoroth View Post
It shouldn't when you're dodging by general evasive movement. This is hardly a novel observation.
It just seems odd to roll an individual defense against each attack when you have no (or little) idea where they're coming from.

Quote:
Originally Posted by Ulzgoroth View Post
Since when?
Martial Arts. Each additional Dodge beyond the first in a given round is at a cumulative -1. Sure, it's an optional rule, but if you want to use it you'll have to give an explicit exclusion for evasive movement.

Quote:
Originally Posted by Ulzgoroth View Post
That's really easy to fix.
Are you arguing, then, that Predictive Shooting shouldn't be a thing? That's certainly a position one can take, but I don't think we should have to choose between allowing for Evasive Movement and Predictive Shooting.

Quote:
Originally Posted by Ulzgoroth View Post
A skill penalty only makes any sense when the travel time is too short to actually evade in so it's a matter of the attacker shaving their aimpoint response time so as not to get faked out.
Seeing as that's probably going to be the case for the vast majority of firefights, I'm fine with that.
Varyon is offline   Reply With Quote
Old 03-23-2016, 11:03 AM   #86
Anthony
 
Join Date: Feb 2005
Location: Berkeley, CA
Default Re: Dodgin' Bullets

Quote:
Originally Posted by Varyon View Post
Seeing as that's probably going to be the case for the vast majority of firefights, I'm fine with that.
Problem is that it's also true for the vast majority of melee combat, so the overall conclusion is to delete the concept of active defenses and handle everything with skill penalties. Which is not clearly wrong, but dramatically changes the entire flow of GURPS combat.
__________________
My GURPS site and Blog.
Anthony is offline   Reply With Quote
Old 03-23-2016, 11:06 AM   #87
Ulzgoroth
 
Join Date: Jul 2008
Default Re: Dodgin' Bullets

Quote:
Originally Posted by Varyon View Post
It just seems odd to roll an individual defense against each attack when you have no (or little) idea where they're coming from.
Is there any actual reasoning for this?

It is, in a very real sense, a passive defense.
Quote:
Originally Posted by Varyon View Post
Martial Arts. Each additional Dodge beyond the first in a given round is at a cumulative -1. Sure, it's an optional rule, but if you want to use it you'll have to give an explicit exclusion for evasive movement.
Fine. I've never seriously considered using that rule in the first place, but certainly don't use it with evasive movement unless the attackers are doing some sort of coordinated firing pattern to blanket your evasion options.

EDIT: Second thought: Actually, maybe you should use it. Instead of representing a saturation of your ability to respond to multiple threats, it's a saturation of the space you could potentially (randomly) move into. Multiple attackers will tend to do that purely by accident/firing at slightly different times/having different guesses about your movement pattern. A coordinated firing pattern might upgrade it to -2 per attacker, if you take this angle!

Of course it's not realistic that the one most likely to land a hit is the last one in the initiative line, but that's a general issue with GURPS combat sequencing, not a specific glitch here.
Quote:
Originally Posted by Varyon View Post
Are you arguing, then, that Predictive Shooting shouldn't be a thing? That's certainly a position one can take, but I don't think we should have to choose between allowing for Evasive Movement and Predictive Shooting.
It shouldn't be a thing against evasive movement.

It seems fine against the 'I see you attacking and defend' type of thing, though I would consider it to be as much Deceptive as Predictive.
Quote:
Originally Posted by Varyon View Post
Seeing as that's probably going to be the case for the vast majority of firefights, I'm fine with that.
I'm not fine with making the rules broken for everything else, and I don't know whether significantly shaving that reaction time is actually possible...
__________________
I don't know any 3e, so there is no chance that I am talking about 3e rules by accident.

Last edited by Ulzgoroth; 03-23-2016 at 11:11 AM.
Ulzgoroth is offline   Reply With Quote
Old 03-23-2016, 11:45 AM   #88
Varyon
 
Join Date: Jun 2013
Default Re: Dodgin' Bullets

Quote:
Originally Posted by Anthony View Post
Problem is that it's also true for the vast majority of melee combat, so the overall conclusion is to delete the concept of active defenses and handle everything with skill penalties. Which is not clearly wrong, but dramatically changes the entire flow of GURPS combat.
For melee combat, you're typically doing the "Dodge the foe's aim" option, not the "Watch the projectile and Dodge it" one. You mostly watch the target's shoulders and hips to predict where the weapon is going, not the weapon itself (although you do keep an eye on that peripherally, so you can adjust for wrist movements and the like). The only one of my suggestions that potentially does away with an Active Defense is Evasive Movement, and while you certainly can do that in melee, more active options usually work better.

Quote:
Originally Posted by Ulzgoroth View Post
Is there any actual reasoning for this?

It is, in a very real sense, a passive defense.
It's more just a "feel" thing for me, honestly. You roll when you Do Something. Seeing someone swinging at you and getting out of the way is Doing Something. Seeing someone sighting on you and trying to break their aim is Doing Something. Opting to move evasively is Doing Something, but you're not Doing Something when a foe actually shoots at you - you've already Done it. Thus, I feel you should make your Dodge roll (or use some other mechanic) when you start moving evasively, then either use it to determine if any of the bullets aimed at you later hit or use it to come up with a penalty. I favor the penalty option because it represents the foe seeing that you're moving evasively and how well you're doing so, and thus allows them to adjust what they do for it (keep Aiming, hoping they can get in a shot during a lull - which likely will happen at some point; aim at your chest instead of your head, as the former isn't being displaced as much so has a better chance of hitting; etc).

Quote:
Originally Posted by Ulzgoroth View Post
Fine. I've never seriously considered using that rule in the first place, but certainly don't use it with evasive movement unless the attackers are doing some sort of coordinated firing pattern to blanket your evasion options.

EDIT: Second thought: Actually, maybe you should use it. Instead of representing a saturation of your ability to respond to multiple threats, it's a saturation of the space you could potentially (randomly) move into. Multiple attackers will tend to do that purely by accident/firing at slightly different times/having different guesses about your movement pattern. A coordinated firing pattern might upgrade it to -2 per attacker, if you take this angle!
Eh, I probably wouldn't even go that far. Unless the bullets are actually all coming at you at once, a hex that had a bullet passing through it a moment ago is perfectly safe to weave into now.

Quote:
Originally Posted by Ulzgoroth View Post
It shouldn't be a thing against evasive movement.

It seems fine against the 'I see you attacking and defend' type of thing, though I would consider it to be as much Deceptive as Predictive.
Note here you're saying that it's easier to adjust for the random movements of someone who is watching where you're aiming and suddenly does them just as you're pulling the trigger than for someone who doesn't even know you're there and that you've been watching do them for several seconds.

Quote:
Originally Posted by Ulzgoroth View Post
I'm not fine with making the rules broken for everything else, and I don't know whether significantly shaving that reaction time is actually possible...
It's more just that things must be rolled into abstractions in order to make the game playable. In a sense, you have a choice to make - do you want the abstraction to "break" close ranged combat (by not allowing for the shooter to adjust for the target's movements, despite the projectile hitting almost instantly), or do you want it to "break" long ranged combat (by allowing the shooter to adjust for movement that hasn't even started yet when he pulls the trigger/releases the arrow/whatever).
Varyon is offline   Reply With Quote
Old 03-23-2016, 11:58 AM   #89
Ulzgoroth
 
Join Date: Jul 2008
Default Re: Dodgin' Bullets

Quote:
Originally Posted by Varyon View Post
Eh, I probably wouldn't even go that far. Unless the bullets are actually all coming at you at once, a hex that had a bullet passing through it a moment ago is perfectly safe to weave into now.
If the shooters are sequencing their fire such that only one set of rounds is a threat at any given time, I suppose so, but I don't think that's a more reasonable interpretation of the likely situation.
Quote:
Originally Posted by Varyon View Post
Note here you're saying that it's easier to adjust for the random movements of someone who is watching where you're aiming and suddenly does them just as you're pulling the trigger than for someone who doesn't even know you're there and that you've been watching do them for several seconds.
Mostly no - as I said, it's as much deceptive as predictive. If their defense is based on reacting to your attack, you can fool that exactly the same way you can with a melee attack.

Slightly yes - because if you're close enough that they can see you moving to attack and react, you're close enough that they can't actually move randomly (not enough time) and you can potentially read which way they're poised to move. Modulo perceptive capabilities on both sides.
Quote:
Originally Posted by Varyon View Post
It's more just that things must be rolled into abstractions in order to make the game playable. In a sense, you have a choice to make - do you want the abstraction to "break" close ranged combat (by not allowing for the shooter to adjust for the target's movements, despite the projectile hitting almost instantly), or do you want it to "break" long ranged combat (by allowing the shooter to adjust for movement that hasn't even started yet when he pulls the trigger/releases the arrow/whatever).
It seems like a quite arbitrary decision that this is where to draw the abstraction barrier, even though you know it doesn't work.
__________________
I don't know any 3e, so there is no chance that I am talking about 3e rules by accident.
Ulzgoroth is offline   Reply With Quote
Old 03-23-2016, 12:30 PM   #90
Varyon
 
Join Date: Jun 2013
Default Re: Dodgin' Bullets

Quote:
Originally Posted by Ulzgoroth View Post
If the shooters are sequencing their fire such that only one set of rounds is a threat at any given time, I suppose so, but I don't think that's a more reasonable interpretation of the likely situation.
Fair enough. I still wouldn't bother - the fact that multiple foes attacking makes it more likely that one of them will hit is good enough for me - but it's still workable to do it the other way.

Quote:
Originally Posted by Ulzgoroth View Post
Mostly no - as I said, it's as much deceptive as predictive. If their defense is based on reacting to your attack, you can fool that exactly the same way you can with a melee attack.
Deceptive Attack isn't only tricky maneuvers. Waiting for an opening, attacking with less buildup than normal, and so forth are also represented by Deceptive Attack, and at least some of those would be usable against a foe using Evasive Movement.

Quote:
Originally Posted by Ulzgoroth View Post
Slightly yes - because if you're close enough that they can see you moving to attack and react, you're close enough that they can't actually move randomly (not enough time) and you can potentially read which way they're poised to move. Modulo perceptive capabilities on both sides.
Are you suggesting that Predictive Shooting is only available at close range, and that Evasive Movement is only available at long range? What would you suggest to be the range (or, rather, timing) cutoff, and is this a binary switch (beyond n yards, Predictive Shooting is impossible, and you can only Dodge if using Evasive Movement) or something more progressive (beyond n yards, Predictive Shooting is -3 per -1, then -4 per -1, and so forth; closer than n yards, Evasive Movement gives a -1 to Dodge, then -2, and so forth)?

Quote:
Originally Posted by Ulzgoroth View Post
It seems like a quite arbitrary decision that this is where to draw the abstraction barrier, even though you know it doesn't work.
I'm saying that Predictive Shooting against Evasive Movement should be available, because it makes sense at close range. You were (or at least seemed to be) saying that Predictive Shooting against Evasive Movement shouldn't be available, because it doesn't make sense at long range. If we assume we're both correct (that PS makes sense at short range, not so much at long range), then either we have to decide which situation we want our rules to be accurate for ("breaking" in the other situation) or we need to come up with some additional rules for determining if we're in a "short range" (PS available) or "long range" (PS unavailable) situation. Having no good idea how to do the latter, I opted for the former, and felt that things "breaking" at long range was a lesser evil than them doing so at short range.
Varyon is offline   Reply With Quote
Reply

Tags
guns, tactical shooting

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 07:28 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.