Friday, July 22, 2011

What To Do With a Fight

At first glance, it can seem like the question to ask yourself when designing a combat system is "How can we have everyone kill each other?" This is certainly an important question, but I think the real question is quite the reverse. That is, "How can we keep people from killing each other?"

Why? Ok, consider most any other action in an RPG or story. You want to lift a rock? Maybe roll some dice and you lift the rock. Ditto for climbing a rope, charming a barmaid or anything else. But when the action is "Stick my sword in that guy" we're uncomfortable with it being that straightforward, and when it comes to the other guy trying to stick his sword in us, then we definitely don't want it to be that simple.

So with that in mind, the real purpose of the combat system is to make the process of killing someone take enough time and effort to complicate matters without making things un-fun. That is, I admit, a kind of callous and disturbing take on it, but the role of violence in RPGs is a bit of a messy topic (and one I'm not really going to drill into at the moment).

On the "not making thing un-fun" front, many systems put a subtle (or not-so-subtle) thumb on the scales in support of the idea that the PCs are going to win any fight they engage in, albeit at some cost. This is a tricky balancing act because we instinctively want a "Fair fight" but we also want a fight we can win. This is the sports movie paradox, and it pops its head up in RPG design in a lot of odd places. This is a big issue, but it's also a high level one, which makes it hard to address at this point.

In terms of complicating violence, the trick is that the heart of a combat system is not dealing damage, it's damage mitigation. Not that dealing damage in unimportant, but rather it's simple and straightforward, and if that's all there was to it, then combat would just be back to the straightforward "I put my sword in his gut". Mitigation is all the reasons that you can't put your sword in his gut, or that it doesn't end the fight when you do.

Classically, this divides into two things - defense and resistance - though that is a division born out of tradition more than necessity. Defense is all the reasons why something wouldn't hit you (that is to say, have no subsequent mechanical effect) while resistance is all the reasons that a hit doesn't end the fight (such as damage reduction or hit points). This sounds tidy, but historically it's very muddled. Consider the role of armor - is it a function of defense or resistance? You can make a case for both (and, indeed, in some systems it has elements of both) and in doing so you highlight the division.

There's a reason that this model lines up with a similar two-part model for offense - roll to attack + roll to damage. They're opposite sides of the same coin, and a lot of games have streamlined both of these things into a single roll to hit, with damage based on Margin of Success plus some modifier (such as weapon or strength). This is certainly easy, but it tends to encounter predictable problems. Specifically, it tends to make whatever stat covers accuracy into a super-stat, and it does weird things when dealing with weapons at extremes of the damage range (since it can make "0 damage" weapons, like a ping pong ball, lethal).

Unfortunately, the alternate approach of adding more layers of rolls (say, one for attack, one for penetration and one for damage) gets cumbersome quickly, so it's not a solution either. Practically speaking, we're limited to a small number of rolls for an exchange in combat, but at the same time we want it to be more than just a single exchange. So where does this leave us?

Well, let's look at what we have for dice. Right now, our core idea is that a normal success is easy to achieve, and there's not much that's more normal than whacking someone. This means we've got a default assumption that it's pretty easy to hit someone, and I'm ok with that, because it is. And that, right there, speaks to something of a design goal - the purpose of every swing in a fight is to end the fight, so there needs to be a good reason it doesn't.

Having a goal like that is essential to making a combat system do something other than emulate another combat system you're familiar with. That specific idea is a somewhat brutal design goal, and it won't stand on its own, but it's a great start, and it gives us something to build from for the next time.


  1. You forgot that some systems place the burden of evasion on the receiving character. Thus the attck sequence is attack/defense/damage. Hitting is often easy as long as there is no defense. Penetration is conflated with damage. It's the I do/You don't dynamic that often happens in other actions

  2. Interesting!

    I'd like to see a combat system that abstracts combat in the same way that other challenges are abstracted. You will always succeed, but the question is, how?

    Imagine approaching a band of orcs and you roll, not to determine if you kill them, but to determine how you kill them and any repercussions. Do any of them get away? Did they do anything interesting during the fight? Do you have any ongoing conditions afterward?

  3. This is something very close to the surface while designing Hollowpoint and one which we addressed several ways. My ancient essay on guy-vs-guy combat problems shows a lot about our solutions:

  4. @Kuroshima Heh, you're getting ahead of me. Yes, one solution is to make defense play a more active role, and that's weighing on my mind because it absolutely has the right sensibility for fiction, but at the same time, it's one of those ideas that has fallen flat in many of its implementations. So the trick (which I'm chewing on) is where to find the sweet spot between those two points.

    @Brent I think that would probably be easy enough to do, though I wonder how players would react. Uncertainty (Or the appearance of it) seems to be a lot of the appeal of combat. Of course, arguably, you've just described 4e. It's very hard to _lose_ a balanced fight, the question is how many resources you burn doing so.

    @Brad It's total coincidence that I'm lingering on Violence for the Hollowpoint release, but it's a coincidence I'm happy with.

  5. @brent There are a number of indie games that go this route, after a fashion. The mechanic they use is conflict-resolution as compared to the more common task-resolution.
    Essentially, Task resolution has you roll for each task. In combat, that's each attack. Conflict resolution has you roll for the whole fight, and you narrate from there.

  6. Rob, I cheated, I'm a GURPShead, my standard attack routine follows that roll to hit/roll to defend/roll damage pattern.

    In GURPS, for those that don't know, combat rolls, like all skill rolls, are by rolling 3d6 under your skill level, while defenses are either dodge (8 for normal humans, 10 for elite normal persons, and the sky is the limit for Supers), or parry/block (skill/2+3, +bonuses, but bonuses, beyond a very common +1 from the Combat Reflexes advantage, are very rare). Reasonable starting combat skills for dedicated fighters are 14 on the low end (in a low powered campaign) to 18-20 in a higher powered one.

    Assuming combat reflexes (everyone takes it, and it's not a bug, it's supposed to be a fundamental trait for anyone who wants to get involved in combat), and reasonable stats for the appropriate poeer levels, that gives you a parry 11/dodge 10 on the low end, and parry 14/dodge 11 on the high end. Now, Given that the rolls are made with 3d6, success probabilities follow a bell curve, centered 10.5. Now, standard attacks are thus very easy to land (the guy with skill 14 will land the blow, baring penalties, 90% of the time), and thus it's the defense that is the important roll. However, the attacker can take penalties to reduce defenses (-2 tp attack per -1 to the target's defenses), or he can get tricky, and take penalties for called shots (hit location, allowing him to target unarmored locations, and/or cause extra injury by attacking vital areas), extra attacks (called Rapid Strikes), or many more advanced tricks. He can even trade attacks for feints, that are resolved as contests of weapon skills (not attack vs defense), and should the feinting character win the contest, he imposes a -1 penalty to all the target's defense rolls for a round (thus, you can feint, and on your next round, attack while his defenses are down). GURPS is a very explicit system when it comes to combat, and you can actually recreate a fencing match blow by blow.

    Back on topic, here, attacks are assumed to always hit (baring the attacker getting tricky, though it's often the case), and defenses are what actually determines if the attack connects. Then damage is rolled, and armor Damage Resistance (DR) is subtracted from the attack. Penetrating damage then is multiplied by it's injury modifier (a number between 0.5 and 4, depending on damage type and location: Sword thrusts deal Impaling damage, that usually has an injury modifier of x2, swings deal more basic damage, but are cutting, and thus only have an x1.5 injury multiplier, and can't target the vital organs [one of the best targets for impaling attacks, since it changes the injury multiplier to x3], and crushing attacks, like punches, have a basic injury multiplier of x1)

    Oh, and baseline GURPS combat is very dangerous, in that usually 1 solid hit is enough to put a character out of the fight.

    Another system that uses defense rolls, and is far less crunchy, is Fate. There, all attacks are opposed by defenses, and the margin of victory in the attack/defense contest, plus any damage bonuses, is what determines how much stress is inflicted on the victim. (Stress is similar to hit points, but not equal. It's represented by boxes, and if you suffer a 3 point hit, you mark the 3rd box (not 3 boxes, but the 3rd box). If that box is already marked, stress rolls up and you thus mark the 4th, 5th.. box. If you have to mark an non-existing box, you're taken out of the fight, and the victor in the fight gets to narrate what happens to you)


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