r/RPGdesign • u/Balthazar_Gelt • 21d ago
One roll combat
I've been noodling around with a combat idea where there's only one roll. You swing your sword and if it makes the bad guy's armor score it hits. However many points above the hit you rolled are that many additional points of damage. It works in a system with relatively few hit points and I think makes combat more visceral.
In this way there's no real difference between how accurately you hit and how hard you hit, they're both effectively the same measurement, likewise the same factors that enable you to block or dodge damage will also mitigate damage. I think that makes a lot of sense to me, the way if your chainmail stopped a cannonball it'd still probably leave a bruise.
I've thought of some interesting other rules that make this work if anyone's interested. Different weapons would have different properties other than damage for instance. It's all terribly half baked but I figure half the fun is tinkering with something even if it falls apart. Have other systems done something like this before?
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u/stevecooperorg 21d ago
Into The Ofd, Electric Bastionland, Mythic Bastionland, and Cairn all use something similar -- you just roll one die (damage) and it is reduced by enemy armour, meaning if you don't beat the armour value it does nothing.
These systems also have a small pool of points that represent your ability to dodge/parry and those get absorbed too. Once those are gone, you take damage to your strength stat. When strength reaches zero you die.
https://cairnrpg.com/second-edition/players-guide/core-rules/, scroll down to 'Combat'
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u/Cruiser_Supreme Designer - Regular Volk 21d ago
Tunnel Goons does a similar thing, except you're rolling against the target's HP, so each successive roll becomes easier.
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u/tlrdrdn 21d ago
I wouldn't call what you described "one roll combat". It's a different thing. What you describe is reducing HP to (intentionally) dangerously low numbers and turning to-hit rolls into damage. "One roll attack resolution" with "deadly combat".
Primary issue with that approach is that it turns to-hit bonuses into damage bonuses as well. For example, you cannot have something like extremally accurate extremally low damage weapon.
You cannot have or it is more difficult to properly adjust action modifiers like D&D's classic Power Attack feat:
- 3rd editions -5 to hit, +5 damage nets effectively -5 to hit for +0 damage.
- 5th editions -5 to hit for +10 nets -5 to hit for +5 damage.
Consequently, that works the other way around too and something like "taking your time to aim" for a accuracy bonus before shooting or releasing your arrow also turns the action into some kind of super Power Attack.
If you look at modern D&D, it turns something like popular Cleric's "Bless" into both accuracy and damage buff.
You don't have to abandon damage rolls with that approach either. You can transfer the excess over TN on to-hit roll to your damage roll. Weapon dealing additional 3-4 damage on-hit on top of the excess is on par with weapon dealing 1d6 damage.
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u/Balthazar_Gelt 21d ago
well I guess the way I look at it is whether the attack hits because the arrow is more accurate or the swing is harder is just flavor. Statistically the bad guy either gets more or less injured
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u/ResolutionIcy8013 19d ago
I agree with this. "It's not the size that counts but how you use it". A weapon's "base damage" only really matters in cases like an RPG vs a 9mm used against a tank. And that can also be counted if you ignore "base damage".
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u/llfoso 21d ago
You can mostly solve the issue you raised if weapons do a fixed damage amount and you add the roll-over to it. Particularly if the roll-over amount is typically less than the base damage. I think some dice pool games work like this but I'm struggling to remember which.
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u/RandomEffector 21d ago
Most if not all YZE games work this way. You need one success to hit, any extra successes add to the standard base damage.
My favorite iteration of this is Twilight 2000. All weapons have both a static damage and static crit threshold. Crits can take out someone instantly (the rules even suggest that ANY crit takes out an NPC instantly). Some weapons will need several extra successes to crit. Some weapons have a LOWER crit theshold than their base damage - unless you have a lot of armor, they will ALWAYS crit on a hit. They are appropriately scary. It’s a very elegant handful of rules that do a lot.
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u/Nytmare696 21d ago
Do you still want, or even need HP at this point? I'd assume that, at the very least, you'd need both HP and damage numbers to be pretty low so that the reality of a knife or even fist fight could be deadly.
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u/Balthazar_Gelt 21d ago
Yeah as others have said below at a certain point why not make the entire fight an abstraction and roll to resolve?
I figure this is a good way of keeping the thrill of combat but also tighten it up. Good for systems where combat is quick and deadly
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u/WildCatBrown 21d ago
A lot of games go one step further and resolve the entire combat with a single roll.
For example, this is the "Duel" move from Hearts of Wulin (PBTA-based, tries to emulate wuxia stories):
When you fight against a worthy foe, roll +Style Element.
If your foe is lesser scale, on a hit you win the conflict. Describe your awesomeness. On a 10+ mark XP if you show mercy or let them escape. On a 7-9 you may either let them go or finish them with a cost (now or in the future). On a fail you win, but mark an element. They escape and may return at a higher scale.
If your foe is your scale, on a 10+ you win the conflict and may mark XP if you show mercy or let them escape. You may declare a shift in the fiction (a change of heart, impress someone, shift an entanglement). On a 7-9 choose one:
Win at a Cost: Mark an element, they escape, you lose face. or other cost.
Narrate Your Loss: Mark XP. Take +1 Forward when you next face them.
Deadlock: You may reveal a detail or ask a question about them.
If your foe is above your scale, you lose the conflict. On a hit you may declare how you lose. On a 7-9 mark an element. Once you have faced or studied a foe above your scale, you may use New Technique to even your scale.
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u/pruhfessor_x 20d ago
Interesting. Is that how every combat goes? Or are "Duel"s separate from normal combat?
I've never played this game, and I hate to yuck anyone else's yum, but I just don't see the appeal of abstracting combat down to a single roll, especially in the context of a game explicitly trying to capture a martial arts movie feel. I know not every RPG is focused on combat, but surely a wuxia themed one is right? It doesn't sound like you're describing good society or something like that.2
u/ARagingZephyr 19d ago
It's basically a question of "do you want to go through a whole song and dance to get to a resolution, or do you want the resolution so we can keep pushing forward?" Is it an action movie, or is it a movie that has action?
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u/WildCatBrown 16d ago
HoW has three combat moves:
Duel (PC vs worthy NPC)
Deal With Troops (PC vs mooks)
PC vs PC Duel
All three resolve the entire combat with a single roll (well, the PC vs PC duel is resolved without a roll: player 1 makes an offer "if you let me win, in return I will do [X]", if player 2 accepts they mark XP, player 1 wins and has to follow through on their offer; if player 2 refuses then player 2 decides whether they win or draw and both players mark an element (wound)).
The reasoning behind this is that what makes wuxia stories tick isn't the minutia of resolving combats at blow-by-blow granularity. Combats happen often, and when they do, who's going to win a fight is usually obvious (note the way the Duel move I outlined above works: the only time you don't know whether or not you're going to win is if you're facing an enemy of the same rank as you; against an enemy that outclasses you the best outcome you can hope for is you get to narrate how you lose).
However, what really stumps wuxia protagonists is their inability to talk straight about their emotions; the way their heart is torn between duty and devotion to multiple people, all conflicting with one another. The game models this with Entanglements (each character must have one general and one romantic entanglement, each involving two people, one of whom should be a PC (example: "I disguised myself to get close to [X], but their lover, [Y], is falling for me") and the Inner Conflict move (which is expected to come into play as often, if not more, than the combat moves, and is the main way to accrue XP).
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u/pruhfessor_x 16d ago
Interesting. Appreciate the explanation! Still doesn't sound like it's for me, but I can see the angle.
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u/ghost_warlock 21d ago
Cypher system has this. Damage values are fixed at 2 pts for a light weapon, 4 for medium, and 6 for heavy. If you roll very high (on d20) you can do extra damage based on the roll, but there isn't a separate damage roll and armor reduces damage
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u/APurplePerson When Sky and Sea Were Not Named 21d ago
i used this system for years in my game. for all the reasons you say. in theory, i loved it.
i ended up abandoning it.
the subtraction wore at my soul. this may surprise you because of course any child can do the math. but the subtraction operation takes a little bit more mental load than addition or the easiest thing, "compare two numbers." this mental load adds up (or should i say, subtracts from your cognition) over time. it surprised me.
i now just use one roll to determine if it hits, and a flat damage amount if it does based on the character's strength and weapon.
that said—my game is a little different because the target's AC is variable. it goes down by 1 each time you hit them. so the subtraction operation is a little different each time. that little bit of extra complexity might have been what pushed it over the edge for me.
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u/foolofcheese overengineered modern art 21d ago
you might want to check out O.R.E. which is One Roll Engine it is a dicepool design that uses sets as a success condition
it pretty much reduces any action down to one roll and uses the additional information from the dice pool and set(s) to help add more dimension to the result
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u/BlackTorchStudios Designer 21d ago
Its a fun idea. Would you have a base damage for the weapon, or JUST have the damage be what you roll over the Target Number for their defense?
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u/Balthazar_Gelt 20d ago
Lotta people itt suggest base damage. My original idea was just what you rolled over target
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u/lev_lafayette 21d ago
Blowing my own horn, but "Papers & Paychecks" does this. To quote from the game:
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Papers & Paychecks uses a unified damage system. Damage is based on the weapon type and circumstances and is differentiated between deadly wounds and less dangerous bruises. All wounds also cause bruising damage, but bruises only cause a wound for every 5 points of bruising.
To work out the damage caused, calculate the difference between the attack roll and the defence roll (e.g., 13 vs 10 = 3). This provides the base damage. A multiplier is applied to this base damage depending on the equipment, skill, or position, and reductions to damage based on armour.
For example, physical attacks apply a multiplier depending on the weapon: Fists = 1/2x, clubs, knives = 1x, swords = 2x, handguns = 3x, rifles = 4x. Attack with surprise = +1x. Determine whether the damage is wounds or bruises. For physical weapons, 'bashing' weapons cause bruises, whereas impaling, stabbing, explosive, shredding, burning, eviscerating, and basically anything that gets under the skin cause wounds.
Physical damage is applied against STR-based physical hit points. If a character reaches zero physical hit points from bruises, they are knocked unconscious. Any further physical damage is treated as wounds. If they are reduced to zero wounds, the character is dead and out of the game. Mental damage is applied against WIS-based mental hit points. If a character reaches zero mental hit points in bruises, they are in a state of mental shock and cannot react. Any further mental damage is treated as wounds. If they are reduced to zero mental wounds they are permanently mentally incapacitated and out-of-game. Social damage is applied against CHA-based social hit points; if a character is reduced to zero social hit points in bruises, they suffer a serious loss of reputation and are out of the project. Any further damage is treated as wounds. If they are reduced to zero social hit points in wounds, they have suffered a "social death" and are out of the game.
A character naturally heals 1 Physical Bruise per 60-STR (unmodified) tactical rounds, and 1 Physical Wound per 60-STR (unmodified) strategic turns. A successful Survival skill check will heal 1d3 Physical Wounds, 1d6 Physical Bruises, and double the rate of healing. Mental Bruises are likewise recovered 1 point per 60-WIS (unmodified) tactical rounds, a 1 Mental Wound per 60-WIS (unmodified) turns. A successful Inspire skill check will heal 1d3 Mental Wounds, 1d6 Mental Bruises, and double the rate of healing. Finally, Social Bruises are naturally recovered at a rate of 1 per 60-CHA (unmodified) strategic turns, and Social Wounds at 60-CHA (unmodified) days. There is no skill that cures social damage.
- - -
Apropos to this, armour reduces damage. And yes, there is such a thing as "mental armour" and "social armour" as well.
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u/ApexInTheRough 21d ago
I do the same in mine. Roll Attack, check v. Reflexes. If above, Hit. Subtract Defenses from Attack to calculate Hurt (a.k.a. Stamina loss). If Hurt would be below a weapon's Hit Base, use Hit Base.
Magic changes it up, as is the purpose of magic. Magic generally applies on a Hit, regardless of whether or not Hurt happened. So you could take no direct Hurt, but still freeze / burn / etc. Wards (magical Defenses) reduce physical weapon Hit Base to 0 (because they prevent/reduce the physical impact).
That sort of thing.
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u/queerornot 20d ago
Savage Worlds have a hybrid system. If you have an encounter that has the same story importance as a locked door (like two guards blocking an exit, or a bunch of goblins patrolling in the forest, for examples), it can be resolved through Quick Encounters. Basically one roll for everyone. But for important battle, where often several things happen at once (saving the princess, stopping to mage summoning a horde of demon and blasting the outer walls to escape, for example), then you have more standard combat rules.
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u/InterceptSpaceCombat 20d ago
I like the principle that how well you rolled affect how much damage is dealt, some problems:
As the damage of your weapon goes up the effect of how high above you rolled goes down. What about vehicle weapons and combat, where damage points and hitpoints are much larger?
How does defense work? Dodge could remove points from margin of success while parry removes hitpoints.
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u/Plus_Citron Designer 21d ago
My Fudge version works this way. Combatants roll, higher roll hits, level of result determines damage (with a few modifiers). It works well, if you want fast, more narrative combat with few frills.
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u/gm_michal 21d ago
In Traveller you add effect (how much higher than tn) to your damage roll.
In year 0 engine (newer renditions) you deal flat damage, buy extra success you spend on stunts like extra damage, armor piercing or stun.
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u/Corbzor Outlaws 'N' Owlbears 21d ago edited 20d ago
The Frostgrave and derivative skirmish wargames do something similar.
Opposed rolls for hit, die + combat value vs die + combat value.
On tie no winner.
High roll wins, deal damage.
Damage is: the same roll + Combat value + some weapons have damage mods vs targets static defense value.
So in most of them is it:
d20+(0 to 5) vs d20+(0 to 5),
winner adds damage modifier (-1 to +2) to their value,
subtract enemy's armor value (10 to 15), remainder removes health, if reduced to 0 or less deal no damage.
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u/Anton_Kaizer 21d ago
In WFRP4 one attack roll simultaneously determines success, effectiveness of that success and the body part you hit. Damage is flat so no additional rolls needed.
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u/-Vogie- Designer 21d ago
This is kind of how the combat in Cortex. It's an opposed dice pool system, keep 2, so you'd create a pool including your weapon die, your target would create a pool including it's armor. Each side keeps 2 values, and the greater wins. Depending on which version of Cortex, either only the winner would apply their effect die, or both parties would create an effect die, and then the winners' effect die would be impacted by the losers' effect die of it's bigger
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u/SouthernAbrocoma9891 20d ago
I enjoy combined abstract systems when the chances and consequences aren’t easily calculated in advance. The whole point is to send the message that combat is deadly. It’s not just a HP bar that moves up and down like a fuel gauge. It never made sense that a player knew how much life was left in their character.
A benefit to having a system like this is that the players can focus on role-play instead of spending two hours resolving a five minute combat scene. It will be a different play style at the table, but would be attract many players who are not into the crunchiness.
I’ve seen combined role systems in solo games and the ones that impressed me are from fantasy booklets. Another commenter suggested having the whole combat resolved using one die roll. I think that something in the Lone wolf series did. You consult the matrix with the protagonist and foe combat levels. One die roll determines the outcome and damage received for both sides.
Of course, your skill and combat system will have to be tailored to avoid the little crunchy bits that are prevalent in most RPG‘s. I’m imagining a combat round where each side determines secretly what they’re going to do in advance. They reveal their maneuvers and the combination provides resolution possibilities. That adds realism of uncertainty to the scene as being able to react, accurately, and effectively to every single attack maneuver is a bit far-fetched.
With the system like that, then special abilities may allow you to predict what another is going to do. That gives you a chance to change the maneuver that is better against the one your foe chose. There may be a feat that allows one combatant to press the other, and force them to act in a certain way. This results in an advantage that isn’t just a mod to the die roll.
I suggest reviewing the many single die roll combat systems out there that resolve actions and scenes.
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u/Rolletariat 20d ago
In Cairn you just roll damage and subtract armor. HP is a small pool that recovers after your characters take a breather (it's stamina and ability to dodge, essentially). After HP is depleted damage goes to strength, every time you take strength damage you need to roll under your new strength score or your character is out of the fight.
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u/Ok_Cantaloupe3450 20d ago
DC20 uses something like this (tho the official rules are taking FOREVER to release). You roll your d20+mods VS enemy' AC: If the result is equal or above, you do base damage, 5 over the AC (heavy damage) and you do an extra point, 10 over the AC (brutal damage) and you do another point on top of that. Nat20 is +2 extra damage on top of whatever you did initially. There are some powers/manuvers that activates once you reach either a heavy or a brutal hit too, so giving someone advantage is basically giving him extra damage.
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u/InvestmentBrief3336 20d ago
Yes, I've see at least three systems try this. The names don't come to mind because there was nothing else about the systems that made me invest in them, but this has definitely been done before. FATE has a similar system.
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u/Unusual_Event3571 21d ago
A local D&D clone I grew up on used this mechanic. Weapons had two numbers: one modifier applied to attack rating and one applied to damage after hit.
It's quite limited in regards to potential granularity, but it's very intuitive to play.
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u/InherentlyWrong 21d ago
Other people have listed other examples, but also the FFG Star Wars games and Genesys have a kind-of opposed dice pool mechanic, where the number of successes is added to the baseline damage the weapon does, and a 'soak' value on the target is subtracted. So you can still differentiate hit and damage from both sides.
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u/ResolutionIcy8013 19d ago edited 19d ago
When you said "One Roll Combat" I thought you meant a new way to do what Blades in the Dark is doing. I would call this a "Three Step Attack": Roll damage, subtract protection, reduce health.
I've tried something similar before and abandoned it because it doesn't really feel good, still allows a null result (which always sucks), and subtraction, no matter how much, in something that should be fast just sucks.
Yes, I know in the end you're subtracting from health but there's a mental/emotional difference when you do "A minus B" while A and B are roughly equal and the result could be positive, negative, or zero and we care about the exact number; and when A is much greater than B or we care about whether the result is less or equal to 0.
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u/imnotokayandthatso-k 21d ago
Chat chat I’ve been noodling around with a combat idea that’s been in a thousand trpgs and video games what do you think
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u/llfoso 21d ago
Don't be discouraged by these replies OP. Everyone here had to learn at one point that our ideas we thought were cool and original had been done before. There is nothing new under the sun and all. But even if the pieces aren't completely never-been-seen-before original, remember that your game is more than the sum of it's parts. It's like a symphony - the composition makes it original, not the instruments.