GURPS Mechanics.   Posted by Dragondog.Group: 0
 GM, 17 posts
Mon 21 Oct 2019
at 00:04
GURPS Mechanics
This is going to be a thread covering the mechanical side of what you can do in GURPS. As GURPS only uses six-sided dice, they normally don't specify the type of dice. So they write 3d instead of 3d6 or 2d-1 instead of 2d6-1.

Summary: Roll 3d6 lower or equal to a target number to succeed.

Success Rolls: You make a success roll when you want to perform an action by rolling 3d6 and comparing it to the number that governs the roll. If your roll is lower than or equal to that number, the task succeeds. Otherwise, it fails. You only need to roll when it is meaningful. Turning on your computer doesn't require a roll. Modifiers may change the target number if the task is easier or harder than standard.

I roll for you under three different circumstances. The character wouldn't know if he succeeded (the character is looking for a hidden door). The player doesn't know what is going on (there are people in hiding close by, does the character detect them). And for the game to flow smoothly (as with a Fright Check).

Margin of Success: If your Success roll succeeded, the difference between your roll and the target number is your Margin of Success. E.g. If your target number is 12 and you roll a 9, you succeed and your margin of success is 3.

Margin of Failure: If your Success roll failed, the difference between your roll and the target number is your Margin of Failure. E.g. If your target number is 12 and you roll a 17, you fail and your margin of failure is 5.

Critical Success: A roll of 3 or 4 is always a critical success. A roll of 5 is a critical success if your target number is 15+. A roll of 6 is a critical success if your target number is 16+.

Critical Failure: A roll of 18 is always a critical failure. A roll of 17 is a critical failure if your target number is 15 or less. Any roll of 10 or greater than your target number is a critical failure: rolling 16 compared to 6, 15 compared to 5, and so on.

Quick Contest: A Quick Contest is a competition that is over in very little time. Each competitor makes a success roll. The person with the largest margin of success or the smallest margin of failure win. In a Resistance Roll, the attacker must succeed to win. The difference in results is called the Margin of Victory for the winner.

Regular Contest: A Regular Contest is a slow competition with much give and take. If one succeeds at the success roll while the other fails, that character wins. Otherwise, the competition continues and they roll again.

Hiking: The hiking rules in the Basic set are very lenient regarding how far you can hike in a given day. These rules were updated in High-Tech so that you can hike Move/2 miles per hour under "normal" conditions.

Jumping: You can jump 6 * Basic Move - 10 inches straight up. Add the number of yards you run before the jump to your Basic Move in that calculation, up to twice normal Basic Move. You can jump 2 * Basic Move - 3 feet straight ahead. Add the number of yards you run before the jump to your Basic Move in that calculation. With this running jump, you can jump up to twice as far as the standing jump. If you have the Jumping skill, you can use half of it instead of Basic Move in the calculations. You may need to roll vs. DX or Jumping to make a difficult jump.

Running: Your running speed is your Basic Move modified by your encumbrance. If you are sprinting, or all-out running, you add 20% to your move and check for fatigue loss every 15 seconds. If you pace yourself for long-distance running, your speed is half the sprinting speed and you roll for fatigue loss every minute. To test your fatigue loss, you make a Success Roll vs. the highest of your HT or your Running skill.

Similarly, there are rules for Climbing which set how fast you can climb and what you have to roll, if anything, to do so that varies with what you're climbing. How fast you can Dig, depending on the soil and your gear. How long you can Hold your Breath, depending on what you are doing. How much you can Lift/Move depending on how you do it. How fast you Swim and how well you deal with hazards in water. How far you can Throw things and how much they hurt you if they hit you.

Sense Rolls: You make a Sense roll to notice something. Make a Success roll vs. Per modified by the appropriate Acute Sense advantage. There are other modifiers depending on how hard it is to detect in the current circumstances. Sometimes, you may need to make a second roll to understand what you have sensed. The second roll is compared with IQ if anyone could figure it out, otherwise, you'd have to roll against a skill.

Influence Rolls: You make an Influence roll to deliberately attempt to ensure a positive reaction from an NPC. Diplomacy, Fast-Talk, Intimidation, Savoir-Faire, Sex Appeal, and Streetwise are the different Influence skills you can use and they all work differently or in different circumstances.

Will Rolls: You make a Will roll to deal with a stressful situation or a distraction. Fright Checks are rolled to deal with fear and may result in temporary or permanent changes to your character.

This message was last edited by the GM at 09:19, Tue 03 Dec 2019.

 GM, 18 posts
Mon 21 Oct 2019
at 01:21
GURPS Mechanics - Combat Maneuvers
Generally speaking, the character with the highest Basic Speed acts first in combat. In PbP games, I find it easier to have the PCs act first or last depending on the situation. And that the PCs act in whatever order they post. Though I make exceptions to that rule on occasion.

Summary: A maneuver is a type of action you can take on your turn. Your turn is one second long.

Free Actions: Free actions are things you can do during any maneuver. E.g. talk, maintain ongoing magical/psionic/etc. effects, drop an item, or crouch.

Do Nothing: You stand there and do nothing. You have no movement. You can defend normally, unless you are specifically prevented from doing so.

Move: You just move. You may still take Free actions. You defend normally.

Change Posture: You switch between two postures. Valid postures are: standing, sitting, kneeling, crawling, lying prone (face down), and lying face up. Only standing allows you to move at your full move and attack without a penalty. If you are lying down (face up or down), you must first change posture to crawling, kneeling or sitting, before you can change posture to standing. But going from standing to lying down is a single change posture maneuver. You can change from kneeling to standing as a Step. You have no other movement and you defend normally, with whatever penalty your current posture gives you.

Aim: You aim at a specific target. You get a bonus to hit if you follow up with an Attack or All-Out Attack maneuver. Certain gear and your stance may give additional bonuses. Most of the time you can Step, but you cannot move at all if aiming a braced two-handed weapon. You can defend normally, but you lose your aiming bonus if you do so.

Evaluate: Evaluate is the melee combat equivalent of Aim and gives you a +1 bonus to Attack, Feint, All-Out Attack, or Move and Attack made against your target. Multiple, consecutive Evaluate maneuvers increase that bonus to +2 and +3. You can Step and you defend normally without spoiling your evaluation.

Attack: You attack your target. You can take a Step and you defend normally.

Feint: You can only feint if you can hit a target with your melee weapon and your opponent can observe you. Make a Quick Contest. If your opponent wins the Quick Conest or you fail your roll, the Feint fails. If you succeed and your opponent fails, you subtract your margin of success from your opponent's defense. If both of you succeed, but you win the Quick Contest, the difference of your margin of successes are subtracted from your foe's defense. E.g. if you have a margin of success of 5 and your opponent has a margin of success of 3, you subtract 2 from his defense. Your Feint only works if your next maneuver is an Attack, All-Out Attack, or Move and Attack. You can Step and you defend normally.

All-Out Attack: You attack, but you do not have the option of defending. Your melee options are: Determined which gives you +4 to hit! Double makes two attacks against the same foe. Feint You feint and attack the same opponent, and the feint applies to this attack. Strong does +2 damage or +1 damage per die if you hit with a melee weapon that does ST-based damage. Your ranged attack options are: Determined which gives you +1 to hit. Suppression Fire which sprays an area with automatic fire your entire turn. You can move up to half your Move, but you can only go forward. You cannot defend at all.

Move and Attack: Make a single poorly aimed attack before or after your move. If you are making a ranged attack, that penalty is the worst of -2 and your weapons Bulk rating. If you are making a melee attack, the penalty is -4 and your adjusted skill cannot exceed 9. You move normally, but you have a -2 penalty to avoid falling, tripping over obstacles, etc. You can dodge or block, but not parry or retreat.

All-Out Defense: You defend yourself without attacking. Increased Defense gives a +2 bonus to one defense until your next turn. Double Defense allows you to use two different defenses against the same attack. Parrying with different arms or weapons count as different defenses. If you choose Increased Dodge you can move up to half your Move, otherwise, you can only Step. You defend normally.

Concentrate: You concentrate on one primarily mental task. If you are distracted, you need to make a Will-3 roll to keep concentrating. You can take a Step and can defend normally, but defending yourself is distracting.

Ready: You pick up or draw any item and prepare it for use. Other than readying a weapon, it is used for a number of different physical actions, such as opening a door. Some tasks may take longer than one second to complete and thus requires several, consecutive Ready maneuvers. You can take a Step and defend yourself normally.

Wait: Do nothing, unless the particular event, you specified in advance occurs before your next turn. If the event occurs, you act as you specified in advance. If you react to someone else, this interrupts their turn and they will continue with it after you have completed yours. You cannot move until your Wait is triggered. You can defend normally, but if you were planning on making an All-Out Attack, you must now instead make an Attack.

Summary: Some specifications on how and how much you can move.

Movement: Standing allows full move. Kneeling/Crawling allows Move x 1/3. Lying Down allows Move 1. Sitting allows no move.

Step: A Step is Move x 1/10, rounded up. Move 1-10 gives a one-yard Step. 11-20, gives a two-yard Step.

Space: A human requires one yard of space.

Moving Through Others: You can always move through space occupied by allies in combat. You can move around adversaries if the route isn't completely blocked. A blocked route has to be Evaded.

Evading: Evading is moving through space occupied by an opponent without trying to knock him down. If the opponent doesn't try to stop you, you Evade automatically. Otherwise, you have to make a Quick Contest of DX.

This message was last edited by the GM at 21:42, Mon 21 Oct 2019.

 GM, 19 posts
Mon 21 Oct 2019
at 21:04
GURPS Mechanics - Combat
Summary: You roll for attack and your opponent rolls for defense. If you succeed and he fails, you hit him. A critical hit bypasses defense.

Attacking: Make a success roll to attack. If it succeeds, your opponent makes a success roll to defend. If the roll failed, your attack struck home and you roll for damage.

Melee Attacks: Before you can attack, your weapon needs to be Ready. A one-handed weapon is held in your hand. A two-handed weapon is held in both. Some unwieldy weapons, e.g. the great axe, become unready after attack unless you are extremely strong. A natural weapon is always Ready, unless occupied. A melee weapon can only attack a target within its Reach.

Melee Attack Options: Normally you attack the torso, but you can select another Hit Location. A Deceptive Attack allows you to trade a -2 penalty to your attack for a -1 penalty to your opponent's defense.  You can do this until your attack becomes 10. A Rapid Attack allows you to trade one attack for two attacks at a -6 penalty each.

Unarmed Combat: You fight without weapons. Boxing, Brawling, and Karate are Striking skills. While Judo, Sumo Wrestling, and Wrestling are Grappling skills.

Unarmed Options: Striking is hitting a target without a weapon. Grabbing is grabbing something an opponent is holding. On your next turn, you may attempt to take it from him. Grappling is grabbing a foe's body. Rules/Result vary depending on opponent ST, Posture, and Hit Location. A Takedown is an attempt to bring a Grappled, standing foe to the ground. A Pin is an attempt to pin a foe on the ground whose torso you are Grappling. A Choke/Strangle is dealing damage to the neck of a foe you are Grappling by the neck. A Choke Hold is an attempt to incapacitate. An Arm Lock is an attempt to restrain or cripple a foe's arm after Grappling it. A Neck Snap/Wrench Limb is an attempt to twist an opponent's extremity you have Grappled. A Slam is deliberately colliding with an opponent. A Shove is an attempt to push a foe.

Ranged Attacks: You make an attack with a weapon used at a distance within that weapon's range. Start with your base skill, add the weapon's Acc, if you Aimed, add the target's SM, modify for the target's distance and speed, and modify for the current circumstances. Rate of Fire (RoF) is the number of shots the weapon can fire per attack.

Defending: A successful attack roll doesn't mean that you have hit your target yet. It means that it is good enough to hit, if the target fails to defend. There are three types of active defense. A Block is an attempt to interpose a shield, cloak or similar object between yourself and the attack. It requires a Ready shield or cloak. A Dodge is an active attempt to move out of the perceived path of the attack. A Parry is an attempt to deflect an attack using a weapon or your bare hands.

Defense Options: Retreat means you are moving away from the attacker while you are defending and get a bonus to your defense against melee attacks for doing so. Dodge and Drop means changing your posture to prone and getting a +3 bonus to Dodge ranged attacks.

Critical Hits: If you roll a critical success on your attack roll, your opponent cannot defend and you get to roll on the Critical Hit Table to see if there is any additional effect.

Critical Miss: If you roll a critical failure on your attack or defense roll. If you get a critical miss on an attack or a parry, you roll on the Critical Miss Table. A critical miss on a dodge results in you being prone. If you critically miss on a block, you lose your grip on the shield and must take a turn to ready the shield before you can block again.

Critical Success on Defense Rolls: If you critically succeed on a defense roll against a melee attack, the attacker has to roll on the Critical Miss Table. A critical success on an unarmed parry vs. a thrown weapon indicated that you caught the weapon without hurting yourself.

This message was last edited by the GM at 06:54, Wed 20 Nov 2019.

 GM, 23 posts
Mon 21 Oct 2019
at 22:30
GURPS Mechanics - Damage and Injury
Summary: The damage and resulting injury and HP loss suffered.

Damage: If your attack roll was successful and your opponent failed to defend, you must now make a damage roll. If your opponent has Damage Resistance (DR), it is subtracted from the damage you rolled. So if DR is equal to or higher than the rolled damage, your attack failed to penetrate. Some attacks may cause damage without penetrating. If there is penetrating damage, if your opponent doesn't have DR all damage is penetrating damage, multiply said damage with the Wounding Modifier for its Damage Type the product is the Injury your foe suffers, which is subtracted from his Hit Points (HP).

Damage Roll: Damage rolls in GURPS are expressed as e.g. 2d, 4d-1, and 5d+2. High-damage may be expressed as 7dx4, meaning roll 7d and multiply the result with 4. As GURPS only uses six-sided dice, they normally don't specify the type of dice rolled.

Half Damage (1/2D) for Ranged Weapons: If a ranged weapon has two range statistics, the first is its Half Damage (1/2D) range, in yards. If the target is beyond that range, divide the damage you roll by 2, rounding down.

Armor Divisor: An armor divisor indicates an attack that's especially good or bad at penetrating DR. It's listed in parentheses, e.g. 4d(2). You divide DR with whatever is in parentheses. So with (2), you divide DR by 2, round down, in comparison to the rolled damage. Or in other words, DR works half as well. With divisors like (0.5), the DR is increased against such attacks.

Knockback: Crushing and Cutting attacks can cause Knockback by knocking the target away from you.

Corrosion: An attack that inflicts Corrosion damage, such as acids, destroys one point of the target's DR per 5 points of damage rolled.

Hurting Yourself: Any time you strike Unarmed and hit a target with DR 3+, you may hurt yourself!

Wounding Modifiers: Multiply penetrating damage with the wounding modifier listed below, rounding down. The result determines the injury, the HP lost by the target.
* Small piercing (pi-): x0.5.
* Burning (burn), corrosion (cor), crushing (cr), fatigue (fat), piercing (pi), and toxic (tox): x1 (damage is unchanged).
* Cutting (cut) and large piercing (pi+): x1.5.
* Impaling (imp) and huge piercing (pi++): x2.

Effects of Injury: If you are injured, subtract the points of injury from your Hit Points. With less than 1/3 HP remaining, you halve your Basic Speed and Move, round up, which also reduces your Dodge. With zero or fewer HP left, you must roll vs. HT every turn to avoid falling unconscious. With fully negative HP, -10 HP if you have 10 HP, you must make another HT roll to avoid death each time you lose an extra multiple of your HP, that is at -2xHP, -3xHP, and so on. You die automatically at -5xHP. The sudden loss of HP can have additional effects.

Follow-Up Damage: Some attacks, such as poison darts or exploding bullets, have follow-up damage. This second type of damage that occurs an instant after the primary damage.

Linked Effects: Some attacks have a linked effect. This is a second type of damage or effect that occurs simultaneously with the primary effect.

This message was last edited by the GM at 22:52, Mon 21 Oct 2019.

 GM, 24 posts
Mon 21 Oct 2019
at 22:54
GURPS Mechanics - Special Combat Situations
We're skipping this post for now.

 GM, 25 posts
Mon 21 Oct 2019
at 22:57
GURPS Mechanics - Special Combat Situations
We're skipping this post for now too.
 GM, 26 posts
Mon 21 Oct 2019
at 22:57
GURPS Mechanics - Special Combat Situations
And this one.
 GM, 45 posts
Thu 24 Oct 2019
at 14:14
GURPS Mechanics - Injuries, Illness, and Fatigue
HP Loss:
* Less than 1/3 HP left: Half Speed, Move, and Dodge, round up.
* 0 HP or less: In addition to the above, make a HT roll at the start of your next turn at -1 per full multiple of HP below zero. Failure means unconsciousness. Do Nothing or roll at the beginning of every turn until you fail.
* -1xHP: In addition to the above, you must make an immediate HT roll or die. Failing by 1 or 2 means you are dying, but not dead. Roll again at -2xHP, -3xHP, etc.
* -5xHP: You die!
* -10xHP: Total bodily destruction!

Shock: When you suffer injury, reduce DX and IQ by the HP loss, maximum -4, on your next turn only. This affects DX- and IQ-based skills, but not defense. If you have 20+ HP, your Shock penalty is -1 per HP/10 of injury, round down. 20-29 HP is -1 per 2 HP lost, 30-39 is -1 per 3HP lost, etc.

Major Wounds: A major wound is any single injury greater than 1/2 your HP. Crippling a body part also counts as a major wound.

Knockdown and Stunning: A major wound or injury to head or vitals may cause you to be knocked to the ground and stunned. While stunned, you must Do Nothing and defend at -4.

Crippling Injury: A single injury to a limb, that causes significant HP loss will cripple, destroy, or dismember that limb. Any crippling injury is also a major wound.

Mortal Wounds: If you fail a HT roll to avoid death by 1 or 2,  you are not dead, but have suffered a mortal wound. You are incapacitated, but may be conscious. If you need to make another HT roll to avoid death, any failure kills you. You must make another HT roll to avoid death every 30 minutes. On a critical success, you are no longer mortally wounded, but you are still incapacitated. Surgery can stabilize your mortal wound.

Death: You may want to keep track of HP loss after death. Decapitation or an obviously lethal attack to a helpless or unconcious person is Instant Death. Assume the person instantly drops to -5xHP.

Natural Recovery: 1 day of rest restores 1 HP.

First Aid: Bandaging takes 1 minute and restores 1 HP. Additional and more elaborate treatment restores an additional 1d-1 HP in 10 minutes. A critical success restores max HP. On a critical failure, the target loses 2 HP.

Surgery: Surgery can stabilize a Mortal Wound and repair crippling injuries.

Medical Care: A physician's care can help you heal faster.

FP Loss:
* Less than 1/3 FP left: Half Move, Dodge, ST, rounded up. This does not affect ST-based quantities such as HP and damage.
* 0 FP or less: If you lose additional FP, you lose the same number of HP. Must succeed on a Will roll to do something other than talk and rest. If you fail your Will roll, you collapse and are incapacitated until you have more than 0 FP. On a critical failure, you must make a HT roll. If you fail that roll, you have a heart attack.
* -1xFP: You fall unconscious. You awake when you have more than 0 FP. You cannot have less than -1xFP. Additional FP loss is HP loss instead.

Fatigue Costs: Fighting a Battle, Hiking, Overexertion, Running or Swimming, using Special Abilities, Starvation and Dehydration, and Missed Sleep may result in FP loss.

Recovering from Fatigue: "Ordinary" FP loss requires 10 minutes of rest to return 1 FP. A decent meal may give a bonus or may be required. Sleep may be required.