Design: Exploding Crits
Exploring the Role of Critical Hits in TTRPGs
It’s round 4 of combat and the party’s battle against the Beholder is nearly lost.
In the previous round of combat the party’s cleric perished in the sweeping laser blast of a disintegration beam. The thief, fearing a similar fate, fled the scene. Only Tabitha IV, Rach’s Level 12 Fighting Man, stands between a narrow victory and the shame of abject defeat. With nary a hope nor a healing prayer Tabitha raises her axe and attacks. At the table, everyone’s eyes follow a twenty-sided die as it tumbles through the air.
Finally it comes to a definite stop.
Rach shouts: “A natural 20” and, for a moment, everyone shares in her excitement.
But the GM looks calm and unconcerned.
“With luck like that and you might just live. Now, can you roll to confirm.”
The room goes deadly silent as Rach slowly reaches for the spent die. She takes it in her hands and closes her eyes to say a little prayer.
A d20 tumbles through the air.
“Lightning can strike twice,” Rach whispers, hoping that it’s true.
In terms of dice mechanics, there are few so simple and so enduring as the critical hit. Invented in 1975 for Empire of the Petal Throne, (thank you, wiki!), the mechanic remains mostly intact today in such obscure games as Dungeons and Dragons, Pathfinder, and more. Indeed, a recent episode of Stranger Things featured a DnD session similar to the above example, though, oddly, no one asked Erica to confirm the crit.
Not that I’m complaining. There’s a reason that particular ruling fell by the wayside.
In terms of a design questions, defining critical hits may not be the most important question but it’s certain to impact the flavor of your game. This dissection of various crit methods and their usage is my attempt to make sense of them as vehicles for plot and thrills. As usual, the thoughts expressed here-in are half-baked and wholly my own.
#1 - The Nat 20 (DND, Pathfinder)
Take up a twenty sided die and give it a good shake. Roll it on the table or your surface of choice and hope for a high score! If you score the jackpot the rules say you’ll succeed no matter what(so long as this isn’t a skill check, then the rules will be ignored). Take up some extra damage dice, while you’re at it, just to hammer home how awesome you are at killing things!
In Other Words: Roll 1d20 and hope you roll high.
The Benefit: Simple and satisfying. Pretty rare (one in twenty, two in twenty with advantage) so it always feels special.
Downsides: Rules interactions require exceptions that nobody likes or pays attention to. The existence of a critical hit on a d20 implies the existence of critical failures, which suck. Sometimes you get a crit when it absolutely doesn’t matter. Sometimes you never get one at all.
Proper Usage: The high roll is simple and true and lends itself well to games with lots of modifiers. In general it’s a good system for larger die sizes like the d20 as simple math will mean it remains rare and exciting throughout the campaign. The major benefit, however, is that it taps into the fantasy adventure vibe of classic roleplaying games.
Personal Thoughts: Speaking for myself, the natural 20 feels custom designed for DnD and DnD-alikes and I probably wouldn’t use it in any other context without some modifications. This is the ultimate “cherry on top” mechanic. As a result there tend to be few rules within the larger system that interact with it beyond expanding a character’s crit range, giving monsters crit immunity (never, ever, do this), or extra crit effects that are rarely relevant. If you use this in a game of your own, strongly consider how it can be expanded upon or even made into a legitimate tactical feature within your larger system. You’ll see an example of that later with my self-described “gambit” system.
#2 - The Exploding Crit (Various die pool systems)
Gather a bunch of dice (like, a lot of dice) and roll them all at once. These might be all the same sort of dice or they might be dice of varying values and colors. If you meet or exceed a challenge value or match a bunch of dice to a target number, you’ll get a good result. If you score really high, you’ll get something extra. If you score the highest value on any given die, roll another! Now that’s playing with power, baby!
In Other Words: Roll your dice and look for any high results. For each high result, roll a new die. Repeat this process and either add up the values against a target or count the number of high dice rolled. In either case, the more you roll the better!
The Benefit: Satisfying when you roll exceptionally high. Can offer players excessive successes beyond most other systems.
Downsides: While there certainly are many nuanced downsides to these systems individually, as a whole the major one is, arguably, the sheer number of dice players need to bring to the table. If that isn’t a downside for you than surely the math that follows from an especially lucky crit will be. Sometimes these systems REQUIRE that you score a crit to succeed which, in turn, detracts from the “specialness” of the mechanic.
Proper Usage: Straight up, exploding crits are the crit-lovers version of crits. Seriously if you just LOVE rolling high this is the system for you. That said, it’s rarely all the practical.
Personal Thoughts: IMO exploding crits work best when employed as part of a smaller die pool. In such systems they can be utilized to produce random effects from a list or they might be used to fuel a pool of “stunt points” or some other resource. Roll a six, then roll another to see what happens? Could be fun. Their traditional usage as a sort of “mega-damage” is also neat but you don’t see a lot of systems that explore this territory anymore.
#3 - Matching Percentiles (Various percentile systems)
Take up 2d10. One will represent the tens, the other the ones. Roll two zeros, that’s a result of 100! Now roll against a set value. Did you succeed? That’s good. Did you fail, that’s bad. Check for matches. If you get two of the same number on each die that’s a crit success and things are better than you’d hoped. Did you fail? Then it’s a crit failure and things are MUCH worse. If you’re up against something dangerous, you may not survive.
In Other Words: Look for matches on 2d10 and test your final number against a set value. Success means you achieve greatness. Failure means you get a fumble.
The Benefit: Easy to parse, visually. Can account for both crit failure and crit success with a range of possibilities based on a character’s skill level! Great at emphasizing the swingy-ness of Percentile systems.
Downsides: Percentile systems aren’t right for every game. For a die mechanic that’s fairly mathematical the matching percentiles system fudges the numbers in favor of simplicity. Critical failure isn’t right for every game.
Proper Usage: Honestly I feel anytime you’re using a percentile system you should consider this method. Even as someone who is crit-fail averse, this one works especially well for games featuring horror elements ala Call of Cthulhu or Delta Green.
Personal Thoughts: For all the quirkiness and variety percentile systems offer, matching percentile crits are actually one of my favorite innovations. Why? Simply put they are one of the few crit methods that are both easy to read, make intuitive sense, and exist on a sliding scale. Have a character whose really skilled in something? They’ll get crits more often. Roll for something you suck at? You’re likely to fumble. The only other competing method for these systems is the high roll and, except in edge cases, matching percentiles is tactically, numerically, and emotionally superior. Odd for me to have such strong feelings for a system I will most-likely never utilize but there you have it.
#4 - The Double Six (Powered by the Apocalypse and Forged in the Dark systems)
Take up a number of dice. If this is a PBTA game you’ll almost always be rolling 2d6. If this is Blades in the Dark, it could be anywhere between five and “zero” dice. Roll them. Examine the result. You might add them together along with a modifier or you might just look for the highest die result, (excepting, of course, when you don’t)!
Look for matches. Specifically sixes! If you get one that’s good. If you get two or more that’s even better, a critical success (unless you rolled “zero” dice, anyway)! In addition to whatever you were promised, the GM will throw you a bone. There might even be a special callout in the rules text. Regardless, it’s good to be you.
In Other Words: Roll multiple d6 and look for doubles.
The Benefit: Encourages players to maximize their die pool. Rewards players for rolling their high stats (yay!). Quick and easy to parse, visually. In Blades players can effectively fish for a crit by pushing their die pool to higher and higher values.
Downsides: Rewards players for rolling their high stats (boo!). It will never happen if you’re only rolling one die. In PBTA you generally don’t get the option of a crit without first leveling up a character and taking a special advance.
Proper Usage: The double six is a service oriented crit system. That is to say, it delivers critical hits at about the rate you’d expect from the dice systems that employ it. With that said, the systems it pops up in frequently don’t NEED critical hits, per se. Indeed, most PbtA games don’t even include them as a basic mechanic.
Personal Thoughts: The big failing of the double six, in my eyes, is that it seemingly exists solely to provide players with something they expect. That isn’t a fatal flaw, but it isn’t a compliment, either. Consider that a double six will always FEEL good even without some mechanical bonus and that sensation will ultimately translate into some advantage for players even above and beyond a strong hit or 10+ result. Perhaps that’s what needs codifying in the form of a GM move?
#5 - The Gambit (Experimental FitD/PBTA Concept)
Take up a number of dice. A few d6 will do. Roll them. Examine the result. Regardless of the outcome, you’ll take the highest die result, (excepting, of course, when you don’t)!
Did you get a 6? Even just one? Normally that’d be an unmitigated success, no drawbacks. A success is nice, to be sure, but what if it was better than nice? What if it was a crit!
Give the GM a little something of yours and they’ll give you the world.
In Other Words: Roll one or more dice and look for a high roll. If you got at least one, ask the GM for something extra and they’ll cut you a deal.
The Benefit: Players have the chance to roll a crit even on “zero” dice in Forged in the Dark games. Pushes play towards mitigated success (yay!). Crits happen more or less on demand and, thus, will generally occur when they are needed most.
Downsides: Because players must bargain with the GM, the game master essentially becomes the arbiter of the crit. Pushes play towards mitigated success (boo?). If players ask for something especially dire the player is likely to refuse and may feel like their cool moment was shut down. Crits become less about luck and more about your willingness to enter a devil’s bargain. If you use this system, standard devil’s bargains might cut into the “specialness” of this system.
Proper Usage: The gambit is a mashup of the high roll and the Devil’s Bargain from Joh Harper’s Blades in the Dark of which I am a fan. If you like Forged in the Dark systems, you might like this one, too. Using it properly will require some GM skill in regards to implementing Devil’s Bargains and I’d recommend that some direction be provided to the GM to ensure players always feel they have a fair opportunity to score a crit.
Personal Thoughts: As a mechanic, the gambit pushes players towards a more desperate playstyle and whilst expanding the resources they have at their disposal. Consider it if you’d like to transform crits from chance-based bonus to a full-fledged tactical option with gauges and dials the players can reach. Employing this one may require a bit more forethought and brainpower as it’s availability will have a severe impact on other systems. That said, I thought it up and now I really want to try it out.
Conclusion: In many systems critical hits essentially act as a “cherry on top” for an otherwise straight-forward dice-rolling system but that isn’t their only roll. Whatever system a designer employs, it’s imperative they consider the purpose of their critical hit mechanic and that it not be vestigial. This is especially true when one implements fumbles or critical failures, but I’d recommend against that unless you are specifically going for the “party of dunces” or the “horrific whims-of-fate” vibes.
Oh, and whatever you do, don’t muddy the waters by making crits mandatory for a basic success or by requiring that players confirm a crit. Those elements are best left in the past.
Once again, thanks for reading and if you have any additional thoughts or questions feel free to leave them in the comments! I’d love to hear about any pet-fave crit mechanics that I may have missed.
