Core Mechanics for TtRPGs

During the D&D/WotC OGL crisis, a lot of people began to design their own TtRPGs. So did I. As I go through my design, I will interrogate every assumption I have about how these games work, determine what I like about it, what I don’t, and how I will build my own game that has the working title “Four Color Fantasy TtRPG.” This is Part 1.

In Dungeons & Dragons, as well as a vast number of other games, everything revolves around a single mechanic. The 20-sided dice. Whenever you attempt to do something, you roll this 20-sided dice, called a d20, potentially add a series of modifiers, and compare the result to a, usually predetermined, target. Some systems like to add several modifiers as you become stronger in the game, while some have a few modifiers that increase over time.

Some major complaints with this base system mechanic, is that the odds are too random. There is a 5% chance for every result. By adding modifiers, you increase the floor and ceiling of those results, making it less likely to fall under the “fail” line, but that doesn’t quite take away the core problem.

There are other dice systems in games. In one of my favorite games, Rogue Trader, part of the Warhammer 40K system, they use percentile dice. So you determine what are the odds you will succeed, on a percentage. You might add modifiers to that, and then you roll 2d10, which combined equal a 1d100 dice roll. If you roll lower than the goal, then you succeed, higher, then you fail. This system is incredibly intuitive, because we use percentage chance of success in real life all the time.

A dice pool system is where you gather multiple dice, and add them together. This creates a bell curve, which allows for more consistency in average results.

In the Star Wars RPG system, there are two types of dice, Positive and Negative. This represents the Light Side/Dark Side of the Force that is so inherent to Star Wars storytelling. So you add together the Positive dice depending on your abilities, training, and equipment, then the GM adds to your roll the Negative dice depending on threat and difficulty of the situation. So you roll all these dice up, and there are three different types of results. First, the success or failure of your attempt. Second, the advantage or disadvantage, which are side effects and consequences of your actions. Third is the Triumph and Despair, which are like critical results. So you can have success with disadvantage, failure with advantage, or even success and advantage with a Despair, or failure and disadvantage with Triumph. Or all Positive, or all negative results. Any combination, which allows for a wonderful array of degrees for success and failure. This doesn’t even touch on the Force Dice, but we’ll stop here.

Some games use really cool mechanics, including ones that don’t use dice at all. One game that I would love to play is called Dread, where instead of dice, you use a Jenga tower. This game is designed for horror stories, and so most low risk actions your character can just do. However, anything with an amount of difficulty, you have to pull a block from the Jenga tower. If you pull it out without knocking over the tower, you succeed, however if you knock the tower down, your character dies. Straight up. This leads to the central promise of the game of a tense, suspense, and sudden death horror game. This is designed for one shots, sure, but fun nonetheless.

Another game called Deadlands does use dice, but as the game is set in a Wild West-esque setting, they also incorporate playing cards and poker chips. The Deadlands system and the Savage Worlds system are based on each other, so you might recognize some of it from there. In character creation, you draw cards, and those cards represent your attribute scores. The cards are also used in combat. At the beginning of combat you roll what is essentially an Initiative score, which determines how many cards you have in your hand. Then, whoever has the highest card goes first, and you can take an action for each card in your hand, when the time comes. The Poker Chips are called “bennies” and act like Inspiration or a Fate point, allowing you to reroll the dice. Good roleplay and having a Joker gives you more bennies, so people are throwing chips around the table, and it looks like a poker game with a dealer at times. All of this makes you feel like cowboys in the saloon, the point of the game.

Obviously there are other cool mechanics, like Alice is Missing, which is entirely a texting based game, where you can’t talk to each other except via texting on your phone, but I can’t go through everything here, so I’ll move on.

Four Color Fantasy

In my game, I’ve decided I’ll use a Dice pool, based on the Cortex Prime system. In this game, you collect a pool of dice together, take the three highest results, and compare them to the target, which is also based on dice pool. This creates a bell curve of results, where the average result is far more likely than highs and lows. I love me some randomness in my game, but I like the feeling of consistency and believability. Whenever you do something, especially something you are particularly good at, from an outside perspective it might seem like you are doing several things at once.

My example is golf. In golf, you walk up to the ball, and swing the stick, trying to hit the ball hard. Having a simple modifier to represent experience doesn’t capture all of the tricks you use in that one action. You have to set your feet right, and twist them, you have to bring your arms back and not bend them, you have to keep your eyes down even after you hit the ball, etc etc etc. I want to feel all of these little actions as I roll a big pool of dice.

So whenever you are taking an action, you compile a pool of dice, each one representing some aspect of what you are doing. However, for speed of the game, I don’t want to add together a dozen dice, because that can really slow the game down. So instead, you quickly glance for the highest three results, and add those together. Compare that to the target number, and that will tell you whether or not you succeed.

Criticals and how to set the target number will probably be it’s own article. So now we have the core mechanic of this game, from which everything else is built.

What is your favorite core resolution mechanic for a TtRPG? Let me know in the comments below!

One comment

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s