More Dice 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 2.

In Part 1 I wrote about how I chose the core mechanic of my game. Short version is you build a dice pool for each roll, and use the 3 highest results, and compare that to the difficulty to see if you succeed.


Now that we know how the mechanics work, we next need to figure out how to set the difficulty of tasks. In 5e, this is a Difficulty Class for skills, Armor Class in combat, and then the occasional contested roll.

Armor Class is a great example of something that speeds up combat, but feels static for players. Because defending an attack is a passive action, something you just do naturally, nothing needs to be decided in the middle of the fight, but players will just sit there and take the hit. Some of them might have a reaction to defend themselves, but the majority of situations the DM tells you what they rolled, and you just say if that hits you or not.

Some people have created a more active defense, where the monsters have a set To Hit number, and the players roll to defend. It works just like rolling to hit, but the effects are reversed. Now the players are doing all of the rolling, and they are more engaged when it’s not their turn. I like the idea, but it doesn’t quite hit the mark for me.

Instead, I really like going all in on Contested Rolls. So when one person wants to hit another, then both parties roll a dice pool, and the winner succeeds. If the attacker wins, they do damage, but if the defender wins, perhaps they can maneuver their attacker. That adds a fun element of movement on the field, that I’ll get into once we talk about combat. If they tie, maybe nothing happens, but they both get a boost on their next roll, to get the momentum going again. Now, this will absolutely be slower than 5e combat, which people already want to speed up, but I don’t think their problem is how long the combat itself takes, but how long you are waiting in between turns to do something. So again, I’ll have another article on combat later, but I want combat to be more involved, but also bounce between the players more than they do now, so you’re not waiting anywhere between 3-30 minutes for your turn to come back around.

So anytime an action is contested between two people/creatures, it will be called a Contest. What about against inanimate objects, like picking a lock? Well, then we’ll do a Test. Stealing from the Cortex Prime system, that I’m basing my dice system on, you roll against a number of d6s, depending on the difficulty. So if something is Easy, it might be 1 or 2 d6s, but if something is Hard, it might be 5 or even 6 d6s. So the DM rolls those d6s, and it functions similar to a Contest, where you now roll against that number. I’m not committed to this Test level system, but it works for now, until I can get to the playtest phase of my game.



What about when you think a player should have a better chance at something than the rules generally allow? In 5e this is where Advantage comes into play, as well as the occasional modifier. Well, given my dice mechanic, I can think of three different ways to give boosts to a roll.

First is an Upgrade. This is where you can take one of the dice you were about to roll, and change it for the next dice size up. So if you upgrade 1d6, you are now instead rolling 1d8. The average change here is fairly minimal, so I think it’s the equivalent of a +1 or +2 modifier. There is already a lot of math in finding and adding the three highest dice rolls, so I really want to avoid post-roll modifiers as much as possible. You can feel an Upgrade in your hands before you even roll. Of course along with the Upgrade, is the negative counterpart Downgrade. This is a bane, so now you have to choose one of your dice to Downgrade, or the dice might even be chosen for you. Now that 1d6 is only 1d4. I can see both of these being thrown around at will, like a DM granting Advantage because the player roleplayed well.

Next you can Add (name not set). This is where you put another whole dice in your hand. It might be just a lowly 1d4, but I can easily see situations where it might be 1d8, or even higher at higher levels. This is very clear how it helps, because you have more chances to roll a high number, and your odds go up. To me this might be the equivalent of a +3 or +4 modifier, which can be a big deal in the right situations. This of course comes with the negative counterpart Remove, where you have to choose one of your dice to take out of your dice pool before you roll. That is pretty serious.

Lastly, you can Increase (name not set). This is where instead of adding the three highest rolls for your result, you instead get to add the four highest rolls. This can make a major difference, and is a very substantial boon. This would be like a +5 or +6 modifier, if not higher if you have a strong dice pool. This comes with the serious negative counterpart Decrease, where instead of the three highest rolls, you instead can only add two together. That can be downright devastating in a well timed change.


Lastly, almost every game has some form of Critical Success/Critical Failure. This such a major result that it is greater than the sum of it’s parts. You get an additional boost of some kind, usually mechanic. In 5e Criticals come from rolling a 20 or a 1 on the d20, which then has an additional effect. I’m thinking about adding an extra step in here. I seem to be adding extra steps a lot, but I think each one is fun. Again, when the time comes to playtest, if things are taking too long, it’s easy to cut the steps back out, so I’d rather go extra now then try to wedge extra things in later.

So first, rolling the highest and lowest dice result. I first encountered this in Kids on Bikes, but I think Savage Worlds created it, there is a system called Exploding Dice. Whenever you roll the highest result on a dice, you roll that dice again, and add the two results together. This is cool because with smaller dice, like 1d4, it happens more often, allowing for results that are bigger than normal, but with larger dice, especially 1d20, it rarely happens, but when it does you get a big boon. Exploding dice can roll over too, meaning if you roll 1d4 and get a 4, it Explodes, you roll it again and get another 4, it Explodes, and you roll it again and get a 3. The total result is now 11. Then, again in Cortex, if you roll a 1 on any die, that’s called a hitch. So now you will roll that die again, and SUBTRACT the die from your Result AFTER you add together the three highest dice. So if you roll 4d6, and get a 5, 4, 3, and 1, you reroll the 1, which then comes to a 2. So you add the three highest dice (5+4+3) and get 12, but subtract the hitch (12-2) for a final result of 10. This is a lot to do with a single roll, especially if a roll has an Explosion and a Hitch, so I might simplify it later, but I like it in theory.

What about the actual cool effect of the Nat20? Well, I am going to change it to a degrees of success system. So if the target number is a 12, and you roll 12, you succeed. However, if you get more than a certain amount above or below, you get a Critical result. I think I want that amount to be 10, but that really needs to be worked out with math, to see what the level should be. But theoretically, if the target number is a 12, and you roll 22, that becomes a Critical Success, but if you roll a 2, that becomes a Critical Failure. Writing that out 10 already seems too high, so maybe 5? I don’t know, I’ll decide that later. Criticals can allow for special moves or moments decided by the GM, as well as cool abilities for your character. I know one ability I like is in combat, where if you get a Critical on the attack, in addition to the damage you can knock your target prone. Stuff like that is cool and creates a more dynamic battle.

Anyway, that’s a lot more detail on my dice mechanics, but I think that everything revolves around Dice Pools, Tests/Contests, Upgrades/Adds/Increases, Exploding/Hitched Dice, and Critical Effects. That’s a lot of mechanics, but I think it’s robust enough to be used across the game.

What problems do you see with my mechanics? Let me know in the comments below!

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