Roleplaying Game: The dX System
For a few years now I’ve been working on my own RPG system that reflects the things I like about tabletop roleplaying. I had thought to wait and release this as part of a finished game book, but since I’ve already been sharing bits of the rules here on the site, I’m going to go into a bit more detail about how the system works, and talk about some of the design goals and inspirations.
When I first started playing RPGs in the early 80s I was fascinated by the “funny dice” and how you weren’t just limited to a regular “square” dice — you had all these other shaped dice with multiple sides to use in your game. The polyhedral dice made RPGs seem a bit different from regular games, and to this day I still enjoy gaming dice.
Some RPG systems focus heavily on one or more of the dice though. Sometimes it’s 10-sided dice (particularly in % system games), pools of regular 6-sided dice, or quite often over the last decade the 20-sided dice. I like using all of the dice as much as possible, so when I started looking at my own game system that became one of the goals – create something that lets you roll all those funny dice.
I’m also a fan of games that let you know whether you win or lose without making you do very much math. It’s not that the math is hard, it’s that it delays the moment of success or failure and shifts it from dice to math. In a Casino there’s a cheer or a groan as soon as the dice at the craps table stop rolling. In many RPGs that moment could be after a few seconds (or more!) of adding things up. A Casino is more exciting than accountancy (for me anyway) so that was another goal of the game – reduce the math as much as possible, and eliminate post dice-roll math altogether.
Both of these goals led to the solution. Instead of rolling a dice, adding one or more numbers, and comparing it to some target you could front-load the math in the system by keeping a constant target number and varying the size of the dice you’re rolling. This, as it turns out, is known as a dice-step system.
Relatively recently I learned that a few other RPGs also use dice-step system in various ways, most notably Savage Worlds and Serenity. What I’ve noticed about both though is that they still involve either shifting target numbers or post dice-roll math. So rather than move to those systems (which I considered!) I’ve continued working on the dX system.
The dX system (as opposed to the d4, d6, or d20 systems) does not have any modifiers added to the dice rolls, and all rolls have a constant target number of 4. This means that on a regular roll a 4-sided dice (d4) succeeds 25% of the time and a 6-sided dice (d6) succeeds 50% of the time. Dice with a greater number of sides are increasingly more successful.
To allow for more granularity in results and to reflect more complex situations in the game there are also opposed dice rolls. In these situations multiple dice are rolled with the highest result and/or the highest result that is equal or greater than the constant target number of 4 succeeds. A character with a d6 rated skill competing against two opponents with d4 rated skills would roll their one 6-sided dice and hope to exceed the rolls of the two opposing 4-sided dice.
Situations in the game that would affect a character’s chance for a successful outcome modify the size of dice being rolled. The notation +d or -d is used to indicated the dice used should bump up or down “one step”. With a normal set of poylhedral dice this means the steps are: d4, d6, d8, d10 and d12. A d8 rated skill with a +d modifier would indicate that a character rolls a 10-sided dice.
In some more complex situations a dice could be stepped up and down multiple times. This allows you to do all the calculations ahead of time and still use a simple dice roll with a target number of 4 to resolve the check. For example: A d6 rated skill with two +d modifiers and one -d modifier would use an 8-sided dice.
Since most dice sets do not include a d14, d16 or d18, the 20-sided dice is used for any steps above d12. Any results “out of range” of the desired dice-step are simply re-rolled. This is probably sufficient for most games and groups, but it’s entirely possible to use a 24-sided or 30-sided dice for higher steps if you wanted.
Having a system that allows for d24 and d30 rolls makes me very happy. 
For the Weird West campaign classes I’ve been posting, their skills are listed using a dX system notation:
Find/Remove Traps, Pick Locks: d4 (+1 at Levels 3,5,7,9)
This means that at 1st level the character would normally roll a d4, at 3rd level a d6, at 5th level a d8, at 7th level a d10, and at 9th level a d12. The target number to succeed at any of these checks would always be 4. These dice could be stepped up or down due to in-game situations affecting the complexity of the check. The GM could also choose to make any of these “opposed checks” in which they would not only need to match or exceed the target number of 4 – but also the number rolled on the opposing dice.
I’ve written an entire combat system using the dX system, but for our upcoming campaign I’m only going to use it for character skills and continue to use the D&D style system of d20 attack rolls, armor class and hit points. At least for now.
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Have you ever checked out The Window? It does something very similar (with a huge heaping of pretentious crap on the side). The TN is 4 (or lower) and the better you are at something the smaller die you roll. It was also my first introduction to a game where the player named his skills.
When I first encountered Savage Worlds in the game store I took one look and thought, “Oh, someone’s copying the Window’s core system.”
That said, I am a huge fan of static TNs (Lacuna, Houses of the Blooded, nWoD). The game I’m working on does this by making a success 3 evens. Modifiers apply to how many dice you toss.
At one point I thought “Nobody has thought of THIS idea before! I should keep this a secret until I publish it”… but I’ve changed my philosophy on that sort of thing considerably.
Changing the way you roll the dice (number of dice, rerolls, roll under/over, odds/evens, lucky numbers) instead of just layering on more math (now add +23!) is much more appealing to me these days.
I like your idea – you could let the players roll whatever dice they like.
Also, Savage Worlds does the multiple dice, target number 4 thing as well
And let’s not forget that there is already a system called “Tri-Stat dX System”. It’s similar to what you propose, only it uses different dice for different campaign levels (realistic, heroic…) and only has 3 characteristics/attributes/stats/whatever.
I’d heard of Tri-Stat but never heard it called “Tri-Stat dX”. I think it was actually designed by a guy here in town.
Taking a look at Wikipedia’s description of Tri-Stat’s Game Mechanics it really isn’t very similar to the system I posted here. It uses multiple dice, variable target numbers, and includes post-roll math up to +/- 20 on the roll. I’m not sure if the dice used bump up or down one step very often in play either. It lists d4 as mundane, d6 as heroic and d8 as “post-human”.
Cool – I like the “dice step” approach and heartily approve of the application! I encountered the static TN in Houses of the Blooded and would also introduce to you (perhaps) the idea of the wager from the same. In Houses, this is used to allow player narration through adding facts via successful wagers. For example, if five d10 would be rolled, the player could roll three and wager two: the 3 rolled, when summed must meet or exceed 10 and if successful the player adds 2 facts (beyond the success). This all depends on how much player narration is appropriate for your game, but I could see one wagering one +d step to either be allowed to add something mechanically or even simply execute what they are doing with panache!
Thanks Rob!
I’ve read a few different games that include mechanics for allowing player narration. I think if it’s about things the character is doing, or is they’re ephemeral descriptive elements it can be easy to work into most RPGs. Some types of shared narration can fundamentally change the style of gameplay though, and are better suited for some types of games more than others. For example in a game where players are exploring a location the GM is using a map + key for it might be inappropriate for a player to add narration that they find a secret door, room, item, NPC, etc. On the other hand, if the GM is just ad-libbing everything anyway, then I don’t see why the players shouldn’t be able to improvise story elements as well if that’s something they enjoy.
On the topic of panache – did you see the Kung Fu Showdown at High Noon post? The Combat Maneuvers are a deceptively simple rule (that I can’t take credit for) which I think will radically change the way combat plays out. It both encourages more descriptive narration of the players actions as well as a type of negotiate between the players and the GM. I can see things like “He’s knocked unconcious or I roll d6 damage vs. your 4 hit points” or even “I shoot the revolver out of his hand… or he takes d8 damage” coming up quite often. The great thing about it is that there’s really no limit to what you can negotiate! As long as both the GM and player prefer what you want to narrate more than the roll for damage – you can do it.
Stuart,
That’s exactly the reason I went with evens-odds. My design is influenced by Prince Valiant and Faeries Tale which both use a coin toss/odds-evens mechanic.
It makes it easy to reinforce the setting with appropriate randomizers. The right kind of coins or dice can add a nice bit of flavor.
“The right kind of coins or dice can add a nice bit of flavor.”
Absolutely! My Deadlands Dice will definitely get used in the upcoming Weird West game!
[...] previously posted about some of my ideas around less math, different dice game mechanics, and in general I find the idea of changing the way the mechanic works a bit more [...]
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[...] hit, armour reduces the amount of stamina you lose in combat. The opposed dice rolls would use the dice step mechanic I’ve posted about [...]
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