Finding a fitting dice system

It took a bit of trial and error, looking for a dice system which I think could benefit the gameplay. At first, I tested the very common D20 dice system found in many popular TTRPGs such as D&D or Pathfinder. But quickly decided against it. In the end I decided for a d12 and d6 system, similar to Daggerheart or The One Ring. I enjoyed the use of the two main D12 with additional d6 depending on how experienced you are in a skill.

Reducing the Math

While I enjoy detailed and math-heavy systems, I decided to try to minimize the math required to play the game, mainly so that combat would be faster-paced and less crunchy. The difficulty also came to define difficulty challenges, which are numbers the player has to reach to be able to succeed in a check. Just adding up the numbers on the dice can lead to a huge range of possible outcomes. Even in situations where, despite being highly skilled, you could still fail an easy check. Rolling 2d12 and 10d6 (the absolute total amount of dice you can have for any given check) could roll you between 12 and 84. Way to large of a range.

I then decided to use a half-rolled and half-success pool system. Where the D12 add up the numbers, while the d6 are pooled and counted in successes if rolled 4 or higher. But once again I wasn't too happy with the outcome and decided to go with a total success pool dice. This reduces the math by a bunch, still allows to roll quite a few dice (yay clickety-clack) and keeps the rough system I had in mind.

Every dice, if d12 or d6, now counts as a success if rolled a four or above. Each player starts with a d12. The chance of failing a single success is still at about 25%, but it feels much more natural that most people can actually succeed in the easiest checks. And, having expertise in a skill, i.e. gaining another d12, gives a huge advantage as succeeding in a 1 success check is now up to 93 per cent, much higher chances.

Creating a Difficulty Table

Having found the dice system I like, and providing the feel of success, which I enjoy. I wanted to make a rough table of how difficult each amount of success for a check is supposed to be. This turned out to be more difficult than initially thought. 

In the end I came to this conclusion:

Difficulty Table

I first had to define a standard, off of which I could then define the rest of the difficulties. I made a bunch of chance tables, for rolling 1d12 + a number of d6 from 0 to 10 and write down their chances of success between 1 to 12 successes. 

I used the website anydice.com and this calculation I found online: https://anydice.com/program/39c1a to help me define each step, by hand, there is probably a better, faster and easier way. But I am not the smartest tool in the shed when it comes to calculating chances.

This then resulted in these tables, defining the target number, from 2 to 6, rolling only 1d12 or 2d12 and rolling additional d6 from 0 to 10.

What I then realised is changing the target number, obviously does not change the number of successes required, but the difficulty of achieving them. This can allow me to make a check easier for a skilled player character, without it suddenly making it possible for a lowly skilled character to achieve. I quite liked this result and decided to go with it.

Example

To define a check's difficulty you consult the difficulty table and define its difficulty. The players can have the chances of reducing the difficulty of the check. For example. a group of players would like to climb a wall. Only one player is highly skilled in climbing and could try to climb the wall itself, while the others lack the expertise to do so.

The players can now do two things. They can help the single player to climb the wall on their own, reducing the target number in the process. this can be done by climbing gear. Or the players try to make the climb easier for all, attaching a rope and throw a grappling hook across the wall to have an easier climb, reducing the success difficulty.

This hopefully allows the Chaplain (Game Master) to fine-tune a check and not automatically make it possible for everyone in an instant if climbing the wall is supposed to be a cooperative challenge on how to get everyone across the wall without everyone just rolling the same climbing check.

Conclusion

Personally, I enjoyed the process of finding out which dice system works best for the game, and I am quite happy with the result in my opinion, it is quite an interesting system. It's probably already used by other systems, but it was a fun exploration figuring it out myself.