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Sean Patrick Hagen

Vancouver based programmer who also does stuff with ttrpgs and video games.

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Kids on Bikes: Health in TTRPGs

Recently Jessy and I reviewed Kids On Bikes on our podcast. If you haven’t given it a listen, give it a go:

It’s a pretty fun game! We played House on Poplar Court, a Free RPG Day 2019 module that we both feel is a pretty great intro to the game and the system.

There’s one thing in particular I wanted to talk some more about, and that’s how Kids on Bikes handles health and getting hurt.

Game System Style

There’s a wide range of ways to handle health and damage in tabletop RPGs. It’s kind of a scale, with “simulationist” on one end and “pure narrative” on the other.

Simulationist Games

Simulationist games are pretty much what they sound like. They’re the games that try to simulate as much as possible – resolving something either involves multiple die rolls, lots of dice, tables, or all of the above. These are the games where it’s possible to hit a specific body part and have different effects based on what you hit that body part with and how much damage you did. That’s if you even do damage, some systems go so far as to just have tables that determine the outcome of a hit to each specific body part.

Simulationist stuff can be fun, but it usually adds a lot of book-keeping to my role as the GM. On the one hand there’s no waffling about “how did I hurt the bad guy” – you shot them with a laser and turned their leg to ash, that’s how you hurt them. On the other hand, because these systems tend to be more table driven1, there’s not a ton of room to players at the table (including the GM) to express themselves if it’s not in one of the tables.

And for me, these systems – while neat! – have some definite drawbacks. I’ve already got lots to keep track of when I’m running a game. On top of what the NPCs are doing, what they’re planning to do, what the players are doing and their current status2; now I also have to have a bunch of tables ready to reference? I’ve just found that I can handle a single table, maybe two when I’m in the middle of running a game. Even then, I tend to use them as guides, not exact directions.

An example of a simulationist system in action is the “Chunky Salsa” rule in one of the editions of Shadowrun I’ve looked at. Basically, grenade damage can reflect off nearby walls. A grenade in a small enclosed space turns a character into a fine mist, but it requires figuring out how many times the blast bounces off the walls. Sounds fun until you have to stop combat to do a bunch of algebra.

If you love it, more power to you! It’s just not my cup of tea, that’s all.

Narrative Games

Narrative games go the other direction. Actions are resolved by a single roll, and that roll will often have a grey area of “you succeeded with consequences”. Aka: you did the thing, but something kinda bad still happens. If you’re trying to sneak, maybe you didn’t get spotted but the guards know someone is here. That kind of thing.

Each has their place and type of games they’re best suited for. Simulationist games tend to be more “deadly” – combat is serious and if you’re not prepared your character is probably going to die. Grim and gritty kind of games. Narrative games tend to be more “power fantasy” – combat is a chance to show off your skills and just how dang cool your character is.

Not to say that narrative games don’t have their flaws, either.

While paring combat down to a single roll is great, trying to figure out what that outcome is can sometimes be tricky. Especially if you’re trying to balance “make the PCs look awesome” with “make combat tense and engaging”. You and the player have rolled to determine the output of a climactic fight! Okay, so… Are they injured? Dead? Did some kind of status effect get inflicted that they have to deal with?

Fighting a bad guy known for coating his blades in a slow but painful and deadly toxin is great, but a worthless thing to add if it doesn’t impact the characters in some way after a fight. You can’t have a player character avoid all repercussions by saying “I succeeded in the roll, my character avoided every hit” – at least, not if you want your narrative game to be interesting.

Stuck In The Middle

And then there are the games in the middle of this spectrum that kind of just hand-wave it all. They often do this by just having you track hit points ( usually shortened to ‘HP’ ). Hitting 0 usually means your dead, or about to die. These systems usually have some kind of way to apply conditions that further affect the character during combat. For example, D&D has the ‘poisoned’ status, but it only affects the dice you roll ( you’re at disadvantage ) – no effect on your pool of HP.

Some games don’t fit well into this “crunch to fluff” spectrum. One that springs to mind immediately is Numenera, and there are probably plenty of others. Some games mix and match between the two styles. Maybe you’ve got a game where combat is more on the simulationist side but everything else is more narrative driven. Or maybe a game about being diplomats in a time of war would have an incredibly rules heavy and simulationist system for negotiations and conversations, but combat is narrative ( if it’s in the game at all ).

But for this post I’m going to be focusing on combat in games that are mostly narrative focused, or are rules-light when it comes to combat.

Narrative Freedom In Fights

Kids on Bikes is definitely a more narrative game. Combat is a single roll between two characters – whether that’s a PC and an NPC, or between two PCs; it all works the same.

Stats In Kids On Bikes

Time for a quick digression into the Kids on Bikes stats system.

They use such a simple way for setting up stats that I’m honestly surprised I haven’t seen it elsewhere. Basically, Kids On Bikes is somewhat similar to Powered By The Apocalypse games, where there are a bunch of “playbooks” that give you the basic outline of various character tropes. The only way to choose what stats you get is to choose which character type you want to play as.

The stats themselves where it gets real cool: rather than having static numbers assigned to each stat, one of the die from d4 up to d20 are assigned to each stat. So you might have a character with a d20 in Charm3, but a d8 in Flight4, and a d4 in Fight5. When you make a stat check, you’re rolling against either a difficulty number set by the GM ( checking to see if you make that jump ) or against the result of another character ( fights! ).

A character with a d4 stat has a 0.1% chance of getting a 20 – not impossible, but when it happens it’ll be AWESOME

You might immediately think “so my character with a d4 Flight is never going to successfully run away from anything”, but you’d be wrong. See, Kids on Bikes has “exploding dice”. Roll the max number on your die and still haven’t beaten your target? Pick up that die and roll again until either you get above 20 or fail to roll the highest number on that die. So someone with a d4 can beat a difficulty 10 check, or even a 20 – it’s just pretty unlikely.

If you’re really curious, here’s a nice version of the output of an AnyDice script ( AnyDice is fantastic to better understand dice probability ).

{"grid":{"bottom":"5%","containLabel":true,"left":"2%","right":"5%","top":"20%","width":"95%"},"legend":{"data":["d4","d6","d8","d10","d20"],"top":"10%"},"series":[{"data":[25,25,25,0,6.25,6.26,6.26,0,1.5626,1.5626,1.5626,0,0.390625,0.390625,0.390625,0,0.09765625,0.09765625,0.09765625,0.09765625],"name":"d4","type":"line"},{"data":[16.6666666667,16.6666666667,16.6666666667,16.6666666667,16.6666666667,0,2.77777777778,2.77777777778,2.77777777778,2.77777777778,2.77777777778,0.462962962963,0.462962962963,0.462962962963,0.462962962963,0.462962962963,0,0.0771604938272,0.0771604938272,0.0771604938272,0.0771604938272,0.0771604938272,0.0771604938272],"name":"d6","type":"line"},{"data":[12.5,12.5,12.5,12.5,12.5,12.5,12.5,0,1.5625,1.5625,1.5625,1.5625,1.5625,1.5625,1.5625,0,0.1953125,0.1953125,0.1953125,0.1953125],"name":"d8","type":"line"},{"data":[10,10,10,10,10,10,10,10,10,0,1,1,1,1,1,1,1,1,1,1],"name":"d10","type":"line"},{"data":[8.33333333333,8.33333333333,8.33333333333,8.33333333333,8.33333333333,8.33333333333,8.33333333333,8.33333333333,8.33333333333,8.33333333333,8.33333333333,0,0.694444444444,0.694444444444,0.694444444444,0.694444444444,0.694444444444,0.694444444444,0.694444444444,0.694444444444],"name":"d12","type":"line"},{"data":[5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5],"name":"d20","type":"line"}],"title":{"left":"center","text":"Dice Exploding Sum Probability","top":"2%"},"tooltip":{"trigger":"axis"},"xAxis":{"boundaryGap":false,"data":[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20],"name":"Number Rolled","nameGap":25,"nameLocation":"center","type":"category"},"yAxis":{"max":25,"min":0,"name":"Percent","nameGap":25,"nameLocation":"center","type":"value"}}

Because the dice explode, the chance of getting the max number on that die is 0 – if you roll a 4 on a d4 you roll again. So the values you can get on a d4 are 1,2,3,5,6,7,… . That’s why the graph goes down to zero before bouncing back up – that’s where the dice is exploding, so that value isn’t counted.

What I find really interesting is the chance of getting a 20 on each of the dice (AnyDice link):

Die % Chance
d20 5
d12 0.6944
d10 1
d8 0.1953125
d6 0.077160
d4 0.09765625

So yeah, it’s easier to get a 20 on a d20. I don’t know about you though, but a character getting to 20 on a d4 sounds way more exciting and nail-biting than rolling a 20 on a d20.

Back To Resolving A Fight

And this is where I think Kids On Bikes reveals how brilliant this system is. See, in lots of other narrative games success is binary – even if there’s a gray area where you “succeed with cost”. It’s pretty much up to the GM and player to have a discussion to figure out what “failing to defend yourself from that rock thrown by the bully” means. And when you’re dealing with narrative games, that rock can mean entirely different things to everyone at the table.

How big was the rock? Was it pointy or smooth? Just how hard did the bully throw the rock? Just how far away were you? Was the bully aiming?

It might just be anxiety on my part, but it feels like because there are so many things that could impact how something plays out, that there is a lot of room for a disagreement to form on how a combat plays out. Now I’ve mostly only played with mature folks who can come to an agreement pretty quickly on how something plays out, but I know there are folks out there who would argue for hours to make sure that the thrown rock was a tiny pebble rather than a fist sized jagged stone.

Kids On Bikes resolves this by using the difference between the two rolls to determine two things:

  • Who has narrative control over the outcome
  • As a rough guide for how injured the defender is if they fail.

So let’s play this out. Let’s say Bob’s character John is getting attacked by the weird slime man who’s been prowling about town. The slime man rolled a d20 and got a 13, and here’s how that could play out depending on how well John rolls:

John’s Roll Result
13 or higher John is fine! The blows missed or just didn’t do any damage. John gets to narrate how it plays out.
Fails by 1 to 3 John is temporarily hurt, or stunned for a moment. GM explains how the slime man attacks, John explains how they mitigated the harm done
Fails by 4 to 6 John is hurt, probably going to need medical attention. Likely dazed or concussed. GM narrates the attack, John narrates how they respond, GM narrates how this barely mitigates the harm
Fails by 7 to 9 John is badly hurt, they need professional help now. GM narrates the attack, John narrates how they respond. GM can alter any of the Johns details as he’s narrating. Then GM gets to explain how the response fails to prevent any harm.
Fails by 10 or more John is either dead, or going to be in the next minute or so. If they somehow survive, there are permanent mechanical effects.

Look at all the guidance! Not just on how John gets hurt, but on how you narrate the outcome! No worrying about “was it a big or small rock” – John failed his roll by 7; it was probably a fist sized rock and it hit him soundly on the head.

Explosive Moments

Now remember how some characters are going to have a small die for the skill they use to attack, and others will have a big one?

Imagine how the table will explode when Bob manages to get a 13 or higher when the stat he’s rolling is attached to a d6 – or a d4! How amazing will that climactic fight be when Mary’s character uses a d4 when attacking and beats the 14 rolled for defense by the slime monster?

To me, those moments are even better than getting a Nat 20 in D&D, because they keep building and building; culminating in an explosion6 of cheers and laughter as your player literally beats the odds.

The Mechanics Of Getting Hurt

For me, this well designed guide of “how much did I just get hurt” is something I love. The lack of it has tripped me up plenty of times when playing other games.

I’ll freely admit that this is a me thing – if you and your table are able to quickly determine what “succeed with cost” means without it delaying your game, awesome! I just find that the guidance means I don’t have to worry about putting a player in a rough spot when maybe the outcome should have been less lethal. And this definitely applies more to narrative games that eschew things like HP or stress boxes; one-page RPGs are definitely where this crops up for me.

I just find that a game that just says “you succeed with cost” without a way to measure that cost creates brain work I don’t want to do and creates anxiety I don’t want to deal with. It’s work because I have to pause the game to try and think of an appropriate outcome: “okay, he was hit by a rock thrown by that troll-like monster, that probably means he’s at least bruised; maybe his arm is broken?".

It produces anxiety because I want my players to have fun, I’m always worried I’m going to drop a consequence on a character that will immediately chill the mood at the table.

For sure, sometimes I want that mood chilling; that moment when the players go “oh shit, this is a serious fight, let’s get down to business7” can be awesome. But only if that’s what you’re aiming for!

Admittedly, if the players think the danger level of a fight is “meh, not too much to worry about” and in your head the danger level is “folks gonna die”, there’s a communication problem around how you as the GM are providing context clues as to how dangerous something is.

And maybe this is a hold-over from starting with D&D! I did get used to being able to use the HP of the party members to determine how to tweak and tune the fight in real-time to ensure they were fun and challenging but not “rocks have fallen yer ded”.

Wrap Up

There are probably plenty of other games out there that have similar systems, or systems that have clear, well-defined guidance on what kind of thing happens when a player succeeds or fails during combat.

Let’s take a step back from the mechanics of a fight – let’s look at something that could happen.

John fires the railgun, and hits the gang member in the elbow. Their arm is severed, and the laser pistol they were holding drops to the ground. Unfortunately for everyone, when it hits the ground it goes off, firing a laser blast! It hits Mary and does some serious damage to her leg – she’s going to need medical attention, and quick!

Now, is that the outcome of a super simulationist game where each thing in that chain of events was the result of rolling on a table the GM kept going until they didn’t have any more tables to look up? Or was that what folks at the table came up with – John’s player narrating the initial attack, the GM narrating what happened when the gun dropped, and Mary’s character narrating how she got hurt?

In the end, neither way is better or worse. What matters is what helps you and your players tell the most fun and engaging stories at your table. Find the system that helps you tell those exciting stories that get retold again and again. And if the system you’re using isn’t as fun or dramatic as the first few pages made it seem; there are plenty more systems out there for you to try.

It’s just that for me, a narrative game where there’s a lot more freedom for players to express their characters without having a giant list of skills8 to remember is great. But that freedom needs to be paired with something that gives everyone at the table guidance on exactly what it means when you failed to defend yourself from an attack ( or seriously botched attacking an enemy ). Whether that’s stress boxes in something like Fate, or using the difference between the dice rolled like Kids On Bikes; I like having some way to know how dire things are getting ( or have suddenly become ) for the players.

I guess where I’m getting at is that having a clear mechanical trigger that lets me go “okay, the monster isn’t trying to kill them, it just wants to wound them enough it thinks it can get away – and that’s happened, so it’s going to retreat now” in my head. Having it be a purely narrative thing is something my brain just isn’t great at gauging the appropriate moment for, so I like having that “hey, now” mechanical moment for it.

Anyways. Thoughts?


  1. In my experience, anyhow. ↩︎

  2. How many times have you accidentally killed a player character because you didn’t realize they were almost nearly dead already? ↩︎

  3. How good you are at charming folks and talking to them ↩︎

  4. How good you are at running away from stuff ↩︎

  5. Pretty sure you get it ↩︎

  6. Pun intended ↩︎

  7. To defeat the huns. ↩︎

  8. Looking at you, D&D. ↩︎


This post was authored by Sean Patrick Hagen on 2021-04-01 12:59:46 -0700 PDT

Wanna see the commit? Go here: ffb9da281eb1912cd106032af43071c8d850a91e