The Dice Roll: Opposed Step-Die

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Choosing the Right System

One key aspect of Sculpt as a system are the die rolls used to determine success and failure. I wanted to use a system that had variable success rates and magnitudes of success and failure. I decided to use an opposed step-die system; one variable die, a d2 through a d12, is rolled against another, and the higher of the two die rolls determines the final outcome. Each roll has an instigator and a target, and if the instigator rolls the higher value, they are successful at performing the action being attempted; if the target’s roll is higher, the target is successful in resisting the action being attempted. I settled on this system by taking into account desirable percent chances of success and failure as well as the feel making a roll has within the game.

Percent Chances of Success

One of the first aspects I had to concretely define were the desired percent chances of success. If I made success too likely, players felt like rolling was trivial and failure was a fluke; if I made success too rare, players felt like rolling was pointless and failure was inevitable. There was a hard balance to strike, but over testing multiple systems, I was able to hone on the thresholds that felt right for Sculpt. Throughout this process, I found that:

• 40-45 percent chance rolls fit well with player expectations of success for a difficult roll.

• Frequent 50 percent chance rolls felt like a character’s abilities were not being taken into account, that only chance is at play.

• 60-70 percent chance rolls fit well with player expectations of success for a fair, or average, roll.

• 70-85 percent chance rolls fit will with player expectations of success for a skilled roll.

• 85 percent chance rolls and higher started to diminish the feeling of rolling for success and instead put the emphasis on “roll to not fail".

Using these thresholds as a guide, I was able to more easily tailor Sculpt’s die system to meet the desired expectations of players. I knew I wanted a more challenging feeling for the game, so I used a system where the percent chance of success is at the lower end each range.

Feel of Gameplay

Another key aspect I wanted to define was the in-game feel of making a roll. Single die rolls, additive rolls, comparative rolls, they all have a unique feel to the player, and based on player feedback, I found that:

• Rolling a single die trying to overcome a success threshold felt like chance was the main opposition to the roll.

• Adding multiple, similar die felt like trying to beat an average or threshold semi-arbitrarily.

• Adding multiple, variable die felt like contributing factors scaled too quickly or not enough.

• Comparing multiple, similar die felt like character traits were either too heavily favored or completely ignored.

• Comparing multiple, variable die felt like character traits were tempered in their range and scope.

Using these player feelings, I was able to narrow in on my desired feel for die rolls that fit with player expectations of a more challenging system. I knew that I wanted a system where a character’s traits directly opposed a target’s, and players should be able to quickly gauge how their character’s traits impact the roll.

These two system aspects, percent chance of success and the feel of gameplay, ultimately led me to the opposed step-die system that Sculpt utilizes. It quite neatly fit within the player’s expected percent chance of success while allowing for growth, and it fit with the feel of gameplay where actions are opposed or resisted, and power is easily gauged by the size of the die being rolled.

Comparing Considered Systems

1d20

The first system I tested was 1d20 + modifier vs challenge rating. This system was both the easiest to manipulate and also gave the largest range in rolls. The flat distribution of roll outcomes that came from rolling a single die provided a strong framework to build on, but I ultimately saw the system as unreliable. Suffering from a known issue with single die systems, there were large swings in outcomes, and the predictability of whether an individual roll would likely result in success or failure was hard to accurately gauge. While the percent chance of success for each roll was easy to determine, each change in modifier or roll represents +/-5%, the feel of the roll didn’t quite fit with the expectations that players had in terms of actions being resisted by similar factors.

2dX

One of the last systems I tested, 2dX vs thresholds of success gave a much more predictable and intuitive roll, but ultimately, the system didn’t provide the right framework for variable success. Rolling 2d4 vs rolling 2d8 have drastically different sums, and this pushed the expected percent chance of success too low for lesser die being rolled in challenging circumstances. While the feel of the roll was within player’s expectations for actions being opposed, the system was brutally unfair to weaker rolls and overemphasized conditional modifiers.

Opposed Step-Die

The system I ended up adapting for Sculpt, opposed step-die hit a sweet-spot in terms of both providing a spread of percent chance of success and the player described feel of making the rolls fit with the opposed nature of the game I was searching for. It combines the probabilities of rolling larger die being more likely to beat a smaller die, and the comparative, rather than additive, function of the roll creates the right feeling of opposition.

Opposed Step-Die Breakdown

Sculpt’s opposed step-die system gives a distinct curve in success rates; rolling a d2 or a d4, regardless of the die you are rolling against, alters the likelihood of success in meaningful ways. Additionally, the comparative nature of each roll means that rolling against varying die alters the average difference of each roll. These two factors combine into a system where the higher the die your roll makes it more likely that you succeed, and more likely that you succeed by a wider margin. Lastly, the opposed nature of the roll creates a mechanical feel of opposition and challenge. Together these traits make the opposed step-die system perfect for what I was trying to accomplish.

Percent Comparison, Average Damage, and Transposed Magnitude

Comparison Key

Top Left: This chart compares the likelihood of success for every roll in Sculpt. In terms of a skill, the rows represent changes in the attack die, and the columns the defense die.

Top Right: This chart shows the average difference in die rolls if the attack die meets or beats the defense die.

Bottom Left: This chart shows the percent chance of the attack die beating the defense die by 3 or more. This is the threshold for activating abilities or adding bonuses to the outcome of a roll.

Bottom Right: This chart shows the expected difference in attack die and defense averaged over both successful and unsuccessful rolls.

The squares encompassing the center 12 entries of each chart denote the most likely dice being rolled during all levels of gameplay.

Game Design Documents

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Below, I discuss a game design document, what it is, when and why you should use one when designing your TTRPG, and how to write one. As part of this discussion, I have included Sculpt’s game design document for your reference as you read on.

Additionally, I have also provided a similar Google Docs template for you to use, should you need.

What is a Game Design Document

Simply put, a Game Design Document (GDD) is a highly descriptive, living document that helps describes a game’s core concepts, themes, mechanics, features, and any other property or idea core to the design. It can be as short as a single page, or, frankly, as long as it needs to be. GDDs outline everything from the scope and concept of a game to reference data and estimated timelines for completion.

More commonly found in the video game industry, GDDs easily serve the same purpose of keeping development unified, focused, and efficient in the tabletop space.

Whenever you undertake designing a TTRPG, there is a good chance that, at some point, you’ll want a reference document that details how your game works. You may want this as material to share with collaborators such as artists, writers, editors, etc. You may need to define what you want your project to be and not be. You may want this document to annotate fleeting ideas that you wish to revisit at a later time, or you may want this document as a primer when you start pitching your project to publishers, crowdfunding, or early-access investors. Whatever the reason, one of the best ways to hash ideas and keep your project moving forward is with a game design document.

When should you use a Game Design Document?

Frankly, there is no one set time that you should use a GDD. The decision to create one is up to you and how you like to work, but, if your project keeps expanding in scope, keeps changing direction or concept, or involves more than just one or two core creators, you should consider using a GDD. Even if you are the only one working on the game, a GDD can be helpful to codify the intricacies of your game for your own reference.

Do you often find yourself adding mechanics that clash with your core gameplay loop?

Do you frequently need to reference an idea later, but want to keep it in the context of your other, existing mechanics?

Do you need to communicate the look, style, feel, or concept of your game with collaborators to get them up to speed?

Do you want a single reference document to look back on as your design your new project?

Do you need a document that helps put timelines and completion dates in the forefront of your mind?

If any of the above sound useful to you, you should heavily consider writing a GDD.

For me, I started my GDD after changing the core mechanics of Sculpt from a 1d20 + modifier system to an opposed roll, step-die system. I wanted to have a document that compile how that one change would cascade through my existing designs. Since then, the GDD has proven more useful to me as, when I am creating a new mechanic or addition, I can quickly reference the GDD to see if the addition is within the same scope, concept, or idea as other mechanics. If it is not, I can easily jot down the mechanic for later and refine the idea when I have time. Having the GDD helped me solidify the tone and feel of Sculpt, as well as kept my work within the scope I set for myself. I quite literally would be months behind in progress had I not written my GDD.

How do you write a Game Design Document?

In theory, writing a game design document is a simple process. To begin, you’ll only need a few key details from your game. Most all GDDs include the game’s title and summary, a system overview that includes core mechanics, desired themes and tones, and a timeline for completion of your game. More complex GDDs include everything from strict definitions of subsystems and secondary mechanics to game art, points of inspiration, and desired player experience. Many include diagrams, reference images of complex ideas, and digitally drawn notes or maps. The limits of what you include in your GDD are only set by you. That being said, start with the basics and add on as you need.

To start, you’ll need to touch on 3 core ideas: introduction, overview, and goals.

The introduction is the quickest part to write; this is the overall summary of your game. Your introduction should include details like a short summary or elevator pitch, the genre and themes you want to emphasize, the basic player experience or core gameplay loop, and any other overarching detail that is vital to your game. Each item in your introduction should only take a couple sentences to describe.

The introduction serves to simplify your ideas and features. If you omitted a specific mechanic or rule from your game’s summary, then you know that that rule is probably not going to be the focus of gameplay and you can probably simplify that rule for your final game. The introduction also serves to communicate the most essential parts of your system by boiling the game down to its barest components. These are the building blocks that you will further build upon in your overview.

The overview is where you start to add detail to your game’s description. Mechanics, core gameplay features, and core formulae are all detailed here. This is where you dive into what makes a subsystem work, the specifics of a mechanic’s function, or the intent behind including a feature in your game. Each of the points in the overview can typically be described in 3 to 5 sentences: ‘The game has this feature. This feature specifically works like this. Here are the circumstances when you would you use this feature.’ Additionally, this section is where charts, graphs, and other tools you use to document your game’s systems are most effectively placed.

The overview serves to guide your efforts most effectively. You can use the individually detailed components as reference to make sure your not investing all your time in a niche mechanic or rule. Your overview also provides you with immediate feedback on the systems that you understand completely, and the systems that require more attention, either due to unfamiliarity or being underdeveloped. All of the components of your overview are, in some way, addressed by your goals.

The goals section is where you rough out a game plan for completing your project. This is where timelines and deadlines come into play. Each overarching subject in your overview section can typically be scheduled such that you minimize the time lost and impact if you need to change a core component. The goals timeline also provides you with an easy way to see how much time you have spent on individual sections or features of your game. This can help put your emphasis into the correct avenues for finishing your game in a timely manner.

The goals section serves to provide a roadmap towards finishing your game. Each component of your game relies on another to be complete, and this roadmap helps prioritize these components in such a way that any change, no matter how large, minimally impacts your work on future sections. All of the components of your overview are, in some way, addressed by your goals.

With these three components written, you have successfully created your game’s design document, but that does not mean that your document is finished. GDDs are meant to be a living document, to be updated and changed as work on your project reveals new aspects you were previously unaware of. Additionally, your document can and should be updated as you flesh out the existing systems in your game. As your document grows, your GDD will serve as a more reliable reference; it will help keep collaborators working with the same structural understanding, and it will help you focus your efforts where they are best utilized or necessary. Hopefully, with this information at hand, you are prepared to make your own game design documents and design systems knowing that remarkable games await!

Sculpt: A System Overview

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Summary: Sculpt, at its core, is a low fantasy, slow growth, tactical choice TTRPG where characters rely on their attributes, skills, and talents to overcome obstacles by using opposed, step-die resolution rolls to determine the magnitude of success or failure.

Low Fantasy: Sculpt’s default fantasy rules include magic and wonder that are relatively grounded. Characters are able to conjure blades and flames and illusions, but none affect the world or mire the mind more than any other mundane skill. An illusory disguise may be quicker to conjure than paint on, but neither is more effective than the other at fooling the mark. Magic flames may sear wounds into a foe, but no more so than being pressed with a lit torch. Blades may be brought forth to bare against fearsome creatures, but conjured or no, the edge cuts just the same. Additionally, magic requires an effect target. Conjuring a blade doesn’t just create a blade from nothing, the blade must previously exist and be available for the conjuring.

Slow Growth: Sculpt’s characters do not become heroes of legend quickly, if at all. Player characters utilize their skills and talents to interact with the world, and each skill or talent takes time to grow and develop. Based on a -1 to +6 ranking system, moving up a single tier of training can be the result of several adventures worth of experience. For context, the rankings of a skill or talent, lowest to highest, are Hindered, Untrained, Novice, Apprentice, Journeyman, Adept, Expert, and Master.

Tactical Choice: Because character growth is slow, players are encouraged to tackle challenges using their characters’ best traits. Teaming up and offering aid have meaningful impacts on gameplay and the likelihood of success increases drastically. Players are encouraged to work together, think creatively, and manipulate situations to favor their chosen abilities.

Attributes, Skills and Talents: Attributes, skills and talents are the three levers players choose between when developing their characters. Attributes are the underlying characteristics a character possesses. Skills are the common abilities available to all characters, and talents are unique advantages that alter a character’s skills in meaningful ways. Two characters with the same attributes and skill training, but different talents, will roll drastically different dice given the same situation and challenge.

Opposed Step-Die Rolls: Each skill a character uses is represented by a single die roll. The die is any even-number faced die with anywhere from 2 to 12 sides. The die roll is compared to an opposing die roll from the corresponding skill of the character’s target. A success is any character roll that meets or beats the opposed roll, and a failure is any character roll that is below the opposed roll. For context, most starting character will roll a 4-sided die (d4) when their skills are used, and a starting character’s best skills will likely use a 6-sided die (d6). The die challenge level of the opposing dice, from lowest to highest, are Simple, Easy, Moderate, Difficult, Daunting, and Impossible, represented by a d2, d4, d6, d8, d10, and d12 respectively.

Magnitude of Success or Failure: Because die rolls are comparative, the magnitude of success or failure is determined by the difference of the character’s die and the opposed die. A player roll of 3 beats an opposed roll of 2 by a magnitude of 1 ( 3 - 2 = 1 ), but a player roll of a 4 fails against an opposed roll of 7 by a magnitude of 3 ( 7 - 4 = 3 ). This variable magnitude determines additional effects and ability triggers to keep large margin success feeling powerful while narrow margin success feel tense and hard won. Likewise, narrow margin failure feels recoverable while large margin failure feels costly.

Over the next several updates, I’ll be digging into each of these in further detail and context as well as providing examples and explanations of how I decided on these mechanics. However, the next update will be Sculpt’s Design Document (along with an explanation of why a Design Document is useful), and remember, it’s never too late to start your own project or finish a system in progress. You never know where remarkable games await!

Project Sculpt

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Welcome all!

It’s no secret that many of us who play tabletop roleplaying games (TTRPGs) have had a desire to create our own systems, and I have come down hard with the creator bug! I am finally making time to finish my passion project: Sculpt. For the longest, time I have wanted a game that captures the breadth of sprawling magic without creating an imbalance between martials and casters, freedom of classless characters, tactical interactions for both combat and social encounters, and an adaptable core ruleset that gives players and game masters alike the agency to tell the stories they are most drawn to. A damn lofty goal, for sure! Along with that goal, I also want to use my experiences in game design, and the steps I took along the way, to serve as inspiration, guidance, and a resource for future creators and developers. With all of that being said, let’s talk Project Sculpt:

What this project will look like:

• Twice weekly updates (most likely Mondays and Fridays, a week update and a weekend update) on my ups, downs, struggles, successes, and any other musings I have along the way to completing my game

• A development journal for my own sake, publicly available to anyone who wants to read and follow along with my journey

• A place for others to come together, gather ideas, be inspired, and, hopefully, get out there and make their own games

• A free and independent source to scour for tips and tricks at every step along the way: concept to idea to playtest to published game

How we get there:

• My biggest commitment is to adding content to the game documents I already have before reviewing and publishing updates on the progress of my week. Without working on the game, I’m effectively going nowhere.

• The updates I do post will include the positives, the negatives, objective and subjective detail, and everything in between. I am under no illusion that this project will succeed without a little bit of luck and good fortune along the way, as well as be setback by things outside everyone’s control.

• It is also my intention to curate an audience for this project by being as open and forthcoming with information and support as I can be.

• Lastly, I want to give those interested a place to routinely come for updates, inspiration, and support as they embark on creating the games they have always wanted to play.

I am so excited to use this project as a learning opportunity for myself and an educational source for others wishing to come along for the experience. I cannot wait to bring the next update here shortly, and I cannot wait to see what remarkable games await!