Saturday, March 18, 2017


[NB: Further reposts of older Heartbreaker posts from back when I did them on my minis blog.]

Last time at Heartbreaker, we talked about expanding the idea of critical hits so that they have a few more possibilities. This expanded notion means that any check can have four results: failure, success, critical failure, and critical success. It might be worth reviewing some definitions from last time.
  • You earn a threat if you roll within the threat range of a particular die check. Earning a threat means rerolling the d20 and adding the result to your check.
  • We can define a threat range of x as any natural die result between [21 -x] and 20. So a threat range of 1 means a natural die result of 20 earns a threat. A threat range of 3 means a natural result between 18 and 20 earns a threat.
  • You suffer an error if you roll within the error range of a particular threat. Suffering an error means rerolling the d20 and subtracting the result from your check. An error is the opposite of a threat. Threats are good; errors are bad!
  • We can define the error range of x as any natural result between 1 and [0 + x]. So an error range of 1 means a natural die result of 1 suffers a error. An error range of 3 means a natural result between 1 and 3 suffers an error.
  • Any check has a difficulty class, or DC. A success means a total result (d20 + modifiers) that exceeds the DC. A critical success is more than twice the DC. Note that earning a threat makes a critical success more likely, but you can get a critical success without earning a threat, or earn a threat without getting a critical success.
  • failure means a total result that does not exceed the DC. A critical failure is half or less of the DC. Again, suffering an error makes getting a critical failure more likely, but the two outcomes are not dependent.
If none of this makes any sense, do reread the last installment!

If it does make sense, you may still want to know how these concepts might apply in a game. Let's apply them to one of the basic encounters of any d20 game; combat. Not every RPG features combat, but I feel pretty sure that combat is central to any d20 system. The d20 concept evolved from classic Dungeons and Dragons, and D&D evolved from wargaming, so combat-free games aren't the best fit for a d20 system.

The basic ideas of d20 combat are probably pretty familiar even to those who've never played D&D. The attacker, lets say a player-character, has an attack score and an amount of damage for a particular attack, usually a die roll of some type. The defender, let's say a GM-controlled monster, has a defense score (often "Armor Class" or AC) plus a number of hit points. The attacker rolls to beat the defender's AC. If he does, he rolls to see how much damage he does, and the defender subtracts the result from his current hit point total. If the defender runs out of hit points, it dies or is disabled.

This system is pretty simple, but it wants for realism. One imagines high-level characters and creatures with a lot of hit points trading direct blows with mortal weapons and not being at all affected, until one arbitrarily collapses in demise. One wishes for alternatives, and some do exist. The most promising alternative for our purposes is the Toughness Save, an idea I got from Green Ronin's True20 system.

I've been trying to speak in generalities in these installments for the sake of those unfamiliar with d20 games, but here I'm going to have to introduce some specifics, namely the idea of Saves. Most d20 games have three saves; Fortitude, Reflex, and Will. Fortitude deals with resisting physical effects and Reflex the ability to dodge and avoid such effects (we'll talk about Will saves later). Fortitude seems to describe roughly the same thing as hit points, and Reflex the same thing as Armor Class (minus the armor). So let's scrap hit points and AC and use Fortitude and Reflex instead. The idea is that when attacking, the player rolls two dice, one for actually making the attack and one to see how much damage it does. And when defending, the player also rolls two dice, one for Reflex to see if he avoids the attack, and one for Fortitude to see how much he resists damage.

That Fortitude save against damage is basically the Toughness Save from True20. True20 features a rather complex damage track that tells you what failing these saves means at various times, but we can actually simplify things a bit now that we have the idea of four flavors of success and failure in mind. I'm going to call this Fortitude save a Damage Save. Here are the possible results of that Damage Save:

  • Critical Success: The attack deals no damage.
  • Success: You gain a hit.
  • Failure: You gain a wound.
  • Critical Failure: You are dying.

Simple right? Except gah, what's this wound and hit business? More terms to learn? Don't worry; they're pretty simple. A hit means that you increase the error range of future Damage Saves by one; the more hits you suffer, the higher the error range until they can be removed. Hits represent scrapes, glancing blows, and other lucky breaks that don't slow you down but can add up to trouble. A wound means that you increase the penalty for all future dice checks by 1. Wounds are more serious injuries that are harder to shake. An easy way to measure hits and wounds is by handing players white or red poker chips (cheap dollar store plastic ones are fine). When the damage is healed, they just hand the chips back.

(Skip this paragraph if you don't care about potential ways to vary this idea. But we could make combat grittier by increasing the penalty to 2, or make it more heroic by making the penalty only apply to Damage Saves and not to all checks. I like the idea of damage having actual effects on one's character, but some players don't like the "death spiral" similar systems feature. But it's optional either way.)

So for succeeding and failing Damage Saves, we've got two different types of damage, both of which impact future Damage Saves in various ways. I get that, you are saying to yourself (hopefully!). I also see how hits and wounds both make critical failure and "dying" more likely, whatever that means. And I see how the error range of these Damage Saves increases based on the number of hits you've suffered. But what's with critical successes equaling no damage at all? And why haven't we talked about threat ranges at all?

Both these questions have the same answer: The threat range of your Damage Save is determined by the armor you are wearing.

As a designer, one thing I'll have to keep clear in my mind is the difference between increasing a bonus (+1 to your check!) and increasing the threat range of a particular check, and why I might pick one over the other for a particular effect. I think that increasing the threat range generally means taking advantage of equipment or some other resource. That's certainly the case with armor. You can almost picture it; if rolling a twenty-sided die is like getting a weapon swung at you, then hitting that threat range range is like your opponent hitting the spot where your armor is doing the most good, like you're some sort of dart board and the dart-thrower just hit a "1." Light armor might have a threat range of 2 or 3, while strong armor could go as high as 10, though it would have other drawbacks.

Now we see what the results of a Damage Save really mean in the game.

  • Critical Success: Your armor absorbs the attack, or you otherwise roll with the blow. No effect.
  • Success: The blow glances off you, leaving you shaken but for the moment unaffected. You gain a hit.
  • Failure: The blow connects, dealing a significant injury. You gain a wound.
  • Critical Failure: Your accumulated injuries have caught up to you, or you have suffered a particularly grievous blow. You are dying.

It's worth pointing out that if you are dealing damage instead of receiving it, the results of that Damage Check are basically the opposite of a Damage Save. Just switch "success" and "failure" above, and replace "you(r)" with "your opponent('s)."

There are other issues that I haven't addressed here, like what attacking and defending are like, and just what dying means. Next time!

[Bonus: Reader Alex Macey asked some questions about how dying and defensive maneuvers like parrying might work with this system. Here's my answer:]

Player death: as stated above, "dying" is a sort of condition that happens when you critically fail a saving throw against damage. If on your turn you are dying, you make a Fortitude save DC 10, or possibly lower pending playtesting! It's like a damage saving throw except without an improved threat range from armor. If I remember correctly, this save vs. death can have these results:
  • Critical success: you stabilize and don't have to make any other death saving throws.
  • Success: Nothing happens, but you need to make another save the next round.
  • Failure: You take another hit.
  • Critical failure: you die.

You could maybe mellow this by saying you have to critically fail twice to die, but that's the basic idea. I think it makes dying a lot more dramatic, as you can never quite be sure when the curtain will fall.

Parrying, etc.: I haven't paid a ton of thought to this, but I like the idea of using what 5e calls "reactions" (think opportunity attacks) to make an attack in lieu of a defense check when attacked. Maybe a critical success means you can riposte! I also like this idea of shields that basically are bad at attacking but great for parrying and other maneuvers.

Sunday, March 5, 2017

Rethinking the critical hit

[N.B. The following is a repost from the brief period when I did my Hearbreaker blogging on my miniatures blog. I wrote this for an audience of people who were mini painters but not necessarily gamers, so if it seems like I'm over-explaining basic d20 RPG concepts, that's why. I link to my first real Hearbreaker post; I'm not going to repost it here, but feel free to take a look if you're interested in some design manifesto kind of stuff.]

My preliminary Heartbreaker post was pretty squishy—big on theory, light on substance. Now begins some actual substance. Let's begin with the critical hit. d20 players are very familiar with how these work, and even non-gamers may have heard the term "natural 20." "Natural 20" means when you roll your twenty-sided die (or "d20"), and a "20" shows on the die (instead of the die roll + modifiers equalling 20). This usually means that you automatically succeed at whatever you were testing, no matter what the actual result. Likewise, rolling a "natural 1" often means automatic failure, again no matter how good the roll might be otherwise. These results can be called "critical successes" and "critical failures." When attacking, a critical success might also result in increased damage, while a critical failure might mean you've dropped your weapon, accidentally stabbed an ally, or worse, depending on the caprice of your gamemaster.

You can see why these rules were put in place. No task is so impossible that success might never transpire through a stroke of luck. And no hero is so competent that he might not suffer the occasional setback. But it seems that a 5% chance of fluke success or failure is a bit much to ask. Even I might play the lottery if there was a 5% chance of winning, and I don't believe anyone would ever step on a plane if it had a 5% chance of crashing. Luckily, there's a way to capture this idea without such wildly swingy odds.

Remember that in d20 games, you roll to beat a certain score, called the Difficulty Class or DC, that is higher or lower depending on the difficulty of the task. Let's redefine "critical success" and "critical failure" around this concept. A critical success is a result that is more than twice the DC of the task at hand. A critical failure is less than half the DC. So I'm attacking a goblin with a defense DC ("AC", for you D&D veterans) of 10. If the result is higher than 10, I've succeeded, but higher than 20, and I've critically succeed and get double damage. Huzzah! But if the result is lower than 5, I've not only failed, but critically failed, and stab myself in the foot. Curses! You can see that a character with a really high attack score is going to get double damage against that goblin all the time, which is already pretty neat and obviates the need for "minion" rules and suchlike. But how would even a mean peon ever score a critical failure?

Let's add a rule that I've heard called the "exploding 20." This isn't my idea, but it goes like this: When you roll a natural 20, you roll the d20 again and add the result to your total. So your modifier is +8, let's say. You roll a natural 20, so your total so far is 20+8=28. You roll again because of the natural 20 and get, say, a 13. So your grand total is 20 (initial roll) +13 (second roll) +8 (your modifier)= 41. Fantastic!

Likewise, you can have an "exploding 1" where if you roll a natural 1, you roll the d20 again and subtract the result from your initial total. So in the case above, if instead you started with a natural 1, your grand total is 1 (initial roll) -13 (second roll) +8 (your modifier)= -4. Against our goblin with a defense DC of 10, that would meet our definition of a critical failure. Better go see a podiatrist.

You could, if you liked, allow for an infinite chain of exploding 20s, creating the theoretical possibility of infinitely high rolls. Let's call this a "chained explosion." You could do the same for exploding 1s, but I find that the most sensible approach—by which natural 20s explode after the initial natural 1—is kind of hard to explain and usually overkill, as 1 -20 +modifiers is usually enough to guarantee critical failure anyway.

Here's another wrinkle; D&D players will know that for certain weapons, you can get a critical hit even if you don't roll a natural 20. A rapier, for example, might do double damage on any natural roll between 18 and 20. Let's call this a threat range of 3. A magically "keened" rapier does double damage on a natural roll between 15 and 20; it has had its threat range increased to 6. If you roll in your threat range, you have rolled a threat.

For our new system, we should say that any natural roll in a threat range should explode. A threat range of 1 works just like our "exploding 20" above, triggering a reroll as described, but a check with a threat range of 3, like an attack with a rapier for example, would also trigger that reroll on an 18 or 19.

We should also consider the opposite concept. An error range of 1 works just like the "exploding 1" above, but an error range of 3, perhaps for an attack with a cursed or poorly-made weapon, would also trigger the reroll for a 2 or 3. If you roll in your error range, you have rolled an error.

Skip this paragraph if you get the concept and don't care about precise mathematical definitions. But for the sake of precision, let's define a threat range of x as any natural die result between [21 -x] and 20, and an error range of x as any natural result between 1 and [0 + x]. A roll within a threat range triggers a threat, a reroll with the result added to the total, while a roll within an error range triggers an error, a reroll with subtraction instead.

Here might be a good place to add that if you are going to use the "chained explosion" rule, the error or threat range of the second reroll is always just 1. That is, if the threat range is 3, and you roll a natural 19 and then a natural 18, the first roll explodes but the second doesn't. Also, if you roll a 1 on the reroll after a threat, you don't then trigger some sort of error within the threat check. That's just silly.

And here's one more quick idea to really expand our minds around the implications of this new way of thinking, which I got from the surprisingly good Swashbuckling Adventures book. You can increase the threat range of any check by up to five, but you also increase the error range by the same amount! So you can gamble to increase the odds of a success or even a critical success, but with the increased chance of critical failure.

So where does this leave us? We basically now have four possible result types for any check: success, critical success, failure, and critical failure. We have the related concepts of threat and error ranges, though it should be noted that you can have a critical success without rolling a threat or a critical failure without rolling an error (and you can roll a threat without getting a critical success!). This makes the simple d20 check a lot more interesting than simple success or failure. But what might these results actually mean in the game? We'll consider that next time!