Here, I'm considering how best to design a non-OGL role-playing game. See my other 2d10 posts.
Dungeons and Dragons famously has six ability scores: Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma. Each ability has a value of between 3 and 18 for humans (originally the result of rolling three six sided dice), and gives a modifier of one for every two points above 10, and a modifier of negative one for every two points below 10.
While this is traditional, it's also old fashioned. If I were to redesign it, I would make the following changes: there is no difference between the ability score and the modifier. Instead, your score is your modifier, and your ability scores go from 0 to 5 (alternatively going below 0 for non-humanoid monsters).
But let's simplify it from six abilities to four. We need a good mix of physical and mental, and of abilities that represent strength and dexterity. So we have an ability for physical strength: Fortitude. And an ability for physical dexterity: Agility. But we also need an ability for mental dexterity: Mind. And finally one for mental strength: Will.
So we have our four abilities. Fortitude is a mixture of Strength and Constitution from D&D. It represents physical toughness and endurance, as well as physical fitness and muscle strength. Agility is most like Dexterity from D&D. It represents flexibility, accuracy, and muscle memory. Meanwhile, Mind is a good match for D&D's intelligence, and maybe the part of Wisdom that relates to noticing things and paying attention. It represents mental adaptability, quickness of thought, reasoning, and recollection. Finally, Will matches for both Charisma and the part of Wisdom that represents willpower. It's force of personality and stubbornness.
When creating your character, players start with 6 points to distribute among their four abilities, and can't put more than 3 in any one. So you could do 3-3-0-0, 3-2-1-0, or 3-1-1-1, and still put a three in your primary stat.
The problem with D&D is that the abilities are not created equal. Almost everyone needs Dexterity (for their armor class), and Constitution for the hit points. But not many characters need Intelligence. Usually you can get by with one specialist for that. And Strength can be dumped by a surprising number of builds, including combat builds relying on Dexterity. For that matter, only one skill depends on Strength. (And none depend on Constitution, but you still need the HP.) But a total of five skills depend on Wisdom.
I'd like to try to balance things out a bit better, with four skills for each ability, for a total of 16. I'd also like to have a few specializations available for each skills, which grant a bonus similar to expertise, but which can be tailored to fit the campaign.
Aside from the abilities, I'll need to consider the secondary stats, such as defense and hit points, and how those are derived. Here's my initial thinking:
- Chance to hit depends on Agility, whether done with a bow or a sword or a spear
- Damage depends on Fortitude, whether done with a bow or a sword or a spear
- There may be some exceptions, with significant downsides. A dagger may depend on Agility for both damage and hit chance, but it doesn't do much damage. A firearm or crossbow may not depend on Fortitude for damage, but they have long reload times.
- I base this at least partially on the fact that firing a bow requires a good bit of strength, which isn't reflected in D&D.
- Defense (AC) depends on a combination of Mind and Agility (probably the maximum for most people, but some unarmored fighting styles may let you add these).
- Health (HP) depends on a combination of Fortitude and Will. I'll probably sum these, as I favor a fairly high starting HP.
- Spells can target any of these defenses.
- Spellcasting can depend on Mind, Will, or both. I think it will probably be both for the pure spellcasters (Mind gives accuracy, Will gives damage), but may work differently for half-casters and others who have more stats they need to raise.
- Many D&D skills can be combined. Lore will cover many kinds of knowledge. Investigation, Insight, and Perception may be covered by one Mind skill. Persuasion and Intimidation can be one Influence skill, and Performance and Deception may fall under the same skill. Specialization can give bonuses to certain sub-skills.
- Rather than expertise, we may have the concept of specialization. That grants a +3 to a skill in a specific situation. When the Performance skill is used for a musical instrument, you may have a specialization. Or a con artist may have specialization to his Performance in weaving a convincing lie. I'm thinking that each background may grant a specialization, as well as a skill.
- I plan to apply degrees of success to everything, including attacks and spells. Getting a higher degree of success does more damage, or has a stronger effect for a spell.
- For weapons, there will be no dice rolls for damage. Instead you add a fixed number between 0 and 5 representing the weapon damage to your Fortitude, and multiply that times your degrees of success to determine how much damage you do.
- I haven't decided whether spells should have the caster roll, or the target roll, or both depending on the spell. When the caster rolls, the more degrees of success, the better for the caster; when the target rolls, the more degrees of failure, the worse for the target.
So let's summarize the skills I have in mind:
- Fortitude Skills
- Athletics - Running, jumping, swimming, climbing, all the things athletes do.
- Labor - Farming, mining, digging pits, anything requiring long hours of backbreaking labor. From clearing collapsed tunnels to building a fortified camp, you'd be surprised how often this comes up in adventuring. And when you're not adventuring, there's always a need for strong backs.
- Survival - Weathering harsh conditions, trekking long distances, and rousing from little sleep to do it again the next day. Includes finding shelter and water as you travel.
- Steering - Sailing a ship, driving a vehicle, or riding a horse all require physical work to steer the vehicle or animal where you want to go.
- Agility Skills
- Finesse - From pick-pocketing to swapping the Gem of Doom for a fake while no one's looking, anything that requires fast hands falls under Finesse.
- Stealth - Moving quietly, keeping to shadows, and slipping through crowds unseen. All of these fall under stealth.
- Acrobatics - From balancing on a wire, to tumbling, to parkour, sometimes quick reflexes save the day.
- Crafting - Making potions, magic items, armor, weapons, food, baskets. They all require careful handling and exacting detail.
- Mind Skills
- Mechanics - Locks, traps, the strange gnomish contraption that looks like it's about to explode. Understanding how things work often allows you to take it apart, and maybe even put it back together.
- Observation - Noticing that you're being watched, spotting the secret door, hearing the beating heart under the floorboards, reading the expression of people and the tells of animals, all this falls under observation.
- Lore - You read. Therefore you know stuff. Maybe even a lot of stuff.
- Arcana - You're sensitive to the flow of magic, able to understand its currents and figure out what it does.
- Will Skills
- Concentration - Remaining focused despite distractions, and people trying to stab you--and sometimes succeeding.
- Influence - Someone said the core of diplomacy is to talk softly and carry a big stick. Whether it's threats or promises, you're good at getting what you want. Applies even when dealing with animals and others who don't share your language.
- Performance - Dancing, singing, playing an instrument, impersonating someone, or weaving a convincing lie. It's all about rejecting another person's reality and replacing it with your own. And if you're convincing enough, you can bring them along for the ride.
- Profession - One might think that having a professional job like scribing or shopkeeping would require one to have a sharp mind. One would be wrong. The primary requirement of such a job is to be able to keep focused, remain polite, and endure the petty slights of customers, bosses, and colleagues, day in and day out.
In addition to skills, players also have specializations. Specializations come from both the class, and from the background. For example, a bard could have a Music specialization in Performance, or someone with the farmer background could have a Farming specialization in Labor. Specializations cover specialized use of skills, and provide a flat +3 on top of the skill bonus. The specialization itself describes what conditions that additional bonus applies in, but ultimately it's up to the DM whether you can use your specialization bonus.
Most of these specializations are described in the backgrounds and class features which grant them, but the DM may allow additional ones. Here are some possibilities to give some ideas:
- Animal empathy
- Magic Items
- Animal Handling
The fifth edition of D&D uses something called bounded accuracy. This limits how high rolls can get by keeping limits on the modifier, since the ability modifier maxes out at 5, and the proficiency modifier maxes out at 6, for a total of +11. Sort of. Then there's expertise, that doubles your proficiency modifier, spells like Bless and Guidance, that add 1d4, and Bardic inspiration, that adds d12. There's also the rogue's Reliable Talent, that causes any roll on the die below 10 to count as a 10. This means, at a minimum, a 10th level rogue with Reliable Talent and Expertise and Guidance and Bardic Inspiration, gets a total 25. On average, they would get about 35. That's a bit outside of bounded accuracy.
How would I control this? For one, I wouldn't grant expertise. I'll instead use specialization that will grant a flat +3 that doesn't scale with level. Second, abilities that would normally grant an extra die will instead grant an extra d10 roll that can replace one of the d10 rolls. (From the Weal pool, if we're using that. I'll probably make the pools an optional variant. If you're not using the pools, this is only limited by the class feature.) So while those will increase the average, they won't increase the maximum.
Otherwise, I'll scale similarly to how 5th edition does. Characters will receive bonuses to their abilities from their ancestry, background, and culture, but the maximum at 1st level for any ability will be 4. Until 10th level, the maximum will be 5, and until 20th, it will be 6. At 20th level, the maximum will increase to 7.
For the bonus from the skill, I think it will work similarly to proficiency bonuses in 5e, scaling with level. At first I was going to use the same scaling as D&D, 1 + level/4 rounded up. However, since I'm starting with a slightly higher ability modifiers, which increase to 7 rather than being limited to 5, and since my average rolls are higher by half (and my ~65% probability is about two points higher), maybe I'll just do level/4 rounded up. So skills will max out at 5, while ability modifier maxes out at 7.
Now, let's do some math, to determine what is Hard, Medium, and Easy for different characters. As a starting point, I consider something where someone has a 75% chance of success to be Easy, where someone has a 50% chance of success to be Medium, and where someone has a 25% chance to be Hard. Now with 2d10, we won't match exactly those numbers, but let's try to get relatively close. Players have a 55% chance to roll an 11 or higher, so we'll define that as our Medium. They have a 79% chance to roll an 8 or higher, but a 2% chance to roll a double 4 or double 5, which would effectively make those values below 8. So an 8 or higher will represent 77% chance of success. Meanwhile, a 2d10 has a a 21% chance of rolling a 15 or higher, +2% for the chance to roll a double 6 or double 7. So a 15 is a hard 2d10 roll, with a 23% chance of success.
So Easy, Medium, and Hard will represent a 77%, 55%, and 23% chance of success. Now let's define our characters:
- Novice: +0 to the roll. No matter the level, no character's trained in everything, and most character's will have one dump stat that remains at 0. When that character is first to make this roll, that's what he does it with.
- Average: +skill bonus to the roll. An Average character may have the skill, but doesn't necessarily have the ability score bonus.
- Gifted: +max ability modifier to the roll. A Gifted character has a maxed out ability modifier, but no training in the skill. Often, he'll be the best choice to make the roll.
- Skilled: +skill bonus + specialization bonus to the roll. Everyone has some specializations, but that doesn't mean that they're naturally talented with the ability. This assumes no bonus from the modifier, but Skilled can also represent someone with skill training and a decent modifier without specialization.
- Adept: +skill bonus + max ability modifier. Some things you're just good at. The Adept has both the max ability modifier and the skill bonus, but doesn't have specialization. You won't always have an adept for every skill, but you'll count yourself lucky when you do.
- Master: +skill bonus + specialization + max ability modifier. Then again, some people have it all. This is the best a character can get without relying on the fortune of Weal dice.
So first, let's consider what sort of rolls are Easy, Medium, and Hard for each character ability level. I selected levels 1, 5, 10, 15, and 20, since that covers are the skill bonuses and ability score maximums.
This gives us some idea of how easy it is to accomplish something. Even at level 1, what's Hard for the Novice character is Easy for the Master, and Medium for the Adept. A target number of 30, however, never ceases to be Hard, even for the Master. Such a task shouldn't be attempted without, at least, some favorable circumstances to help. And a 25 doesn't become Medium for the Master until level 20, and is still hard for the Adept.
In general, I think what's Medium for the Average character should be Easy for the Adept and should be Easy for the Master to achieve with an extra degree of success, and what's Hard for the Average character should be Medium for the Adept and should be Easy for the Master. I think this achieves that.
Where do attack rolls fit on this? Somewhere between Adept (characters are always skilled with their weapons, and usually max their attack roll as much as possible), and Master (as higher level characters tend to pick up magic weapons, that can give them a bonus close to the specialization bonus). Still, it's best not to design with Masters in mind, either for skill rolls or for enemies.
That does bring us to our design space for challenges. In general, I believe that an Easy target number should be Medium for the Novice character and Easy for the Average character, while a Medium target number is Hard for the Novice character and Medium for the Gifted character and Easy for the Expert, while a Hard target number is Hard for the Skilled and Medium for the Master.
Note that the standard 10/15/20 fits this fairly well for that level of difficulty. You can continue using that all the way up to high levels without leaving anyone behind, though it will start to become trivial to the Master, and pretty easy for the Adept. One way to handle that is to add higher levels of difficulty. Here's what I propose:
- Target of 10: Easy Difficulty. Anyone can do it, and most people have a decent chance.
- Target of 15: Medium Difficulty. It takes some luck for the novice to achieve, but every party should have someone with a decent chance of accomplishing it.
- Target of 20: Hard Difficulty. A novice can pull it off. Barely. Most parties will have difficulty accomplishing it.
- Target of 25: Expert Difficulty. If you have an Adept in your party, you might be able to pull it off, but it won't be easy.
- Target of 30: Specialist Difficulty. Only the very best in the world can pull it off, and even they fail more often than they succeed.
Note that something that is Hard difficulty is Expert difficulty to achieve with an extra degree of success, and Specialist difficulty to achieve with two degrees of success. Setting the target of 30 means that your party probably won't manage it. But setting it to Hard, means they have a small chance of getting three degrees of success. Here are the probabilities for each of the character ability levels to accomplish these difficulties at levels 1, 5, 10, 15, and 20.
Sometimes, though, you want to know what will actually be hard for your party. For that, I suggest balancing around Easy for Average, Medium for Gifted, and Hard for Skilled. I personally find this useful for skill challenges, so I know what my players are generally able to handle.
- Levels 1-4: 9 (Easy)/15 (Medium)/19 (Hard)
- Levels 5-8: 10 (Easy)/16 (Medium)/20 (Hard)
- Levels 9-12: 11 (Easy)/16 (Medium)/21 (Hard)
- Levels 13-16: 12 (Easy)/17 (Medium)/22 (Hard)
- Levels 17-20: 13 (Easy)/18 (Medium)/23 (Hard)
This results in the following for the percentage odds of success (including the possibility of doubles, assuming I calculated them correctly):
Easy tasks remain Easy for the Average character (though they eventually approach Hard for the Novice character), Medium tasks fairly Hard for the Average character, and Medium to Easy for the Adept, and Hard tasks are Hard to Medium for the Adept, and approximately Medium to Easy for the Master.
Update (1/19/2023): Figuring out the math is of course an iterative process. I've created a new version based on two different assumptions: one where a Gifted (max ability, no skill) and Skilled (skill and specialization, no ability modifier) represent a more likely highest ability in the party, and one where the standard 10/15/20/25/30 are used throughout the game.