Jorune: Evolutions uses a stat and skill check system that is different than the mechanics used in combat. Since Jorune: Evolutions is OD&D inspired, in another post I tried out a unified mechanic that employs the 1d6 that OD&D uses for most things. It was simple and the math was very transparent in a player-facing way. It also had a certain cleanness to it in that progression is linear and even a +1 opens up the ability to meet challenge levels that were previously closed.
A possible downside is that it makes those low modifiers very significant, especially when it comes to opposed rolls where having an advantage can lead to stacked modifiers. This would have been OK, except for the fact that I'm using opposed rolls for grappling in unarmed combat and giving a +1 modifier for being large sized. (My next post will explain.) This would have resulted in each group having at least one unarmed boccord specialist in it, i.e. a half-giant professional wrestler. That game sounds amazing, but it's not the game I'm trying to design.
The other possibility, with which I originally started, was to use a 2d6 system. This fits with the reaction roll mechanic and downtime system I'm using. Also, as Alistair mentioned in the comments on the 1d6 skills post, classic Traveller used a (janky) 2d6 skill system, so it has a nice pedigree for old school sci-fi gaming. That it picks up the PbtA resonance is a welcome result for me, and Cepheus system games use it as well. If you put a chart--like the one below--that shows the probabilities of success as a percentage chance on the character sheet, then you can make the math transparent enough to the players I hope. And as Tom Killion mentioned, it's fun and more dramatic feeling to roll more dice than one.
Types of Checks
There are four kinds of stat and skill checks in Jorune Evolutions. A roll can be opposed or unopposed. Each of these kinds of rolls can be a straight roll or a mixed roll. The Sholari will tell the player which of these types the roll is, and what modifiers will apply, before the player decides to roll the dice.
Unopposed checks are tests against the PC’s skills or stats where the only opposition are the circumstances of action, inanimate objects, or natural forces. Opposed checks are made when the PC is attempting something that is resisted by another sentient being.
Straight rolls are rolls with binary results: success or failure. (Almost all rolls in classic D&D are straight rolls, with the exception of reaction rolls.) Mixed rolls are made in circumstances where the effect of success is uncertain and feels narratively like it should be a scale of possible outcomes. Since Jorune Evolutions takes inspiration from classic D&D, straight rolls are the default.
Roll 2d6 + stat or skill modifier + difficulty modifier. (Note: it is always a stat OR a skill check. The modifiers do not stack.)
Results (Straight): 6- failure 7+ success
Results (Mixed): 6- failure 7-9 mixed result 10+ Success
+2 Supreme (You can only reach this level through big ticket sandbox advancement)
-1 Untrained0 Trained+1 Skilled+2 Master
Automatic Failure Rule
To make an opposed check, each party roll 2d6 + advantage modifier + stat or skill modifier. The advantage modifier is applied only to the party whose situation is more advantageous. In a straight opposed roll, whoever gets the higher total number prevails. In a mixed roll, consult the winner’s roll to see whether it is a mixed result or a success. A tie always results in a temporary stalemate. (Check again next round.)
Opposed Checks: Each party rolls 2d6 + stat or skill modifier + advantage modifier
Results (Straight): Whoever’s results are higher prevails.
Results (Mixed): Whoever’s results are higher prevails. Consult the winner’s result: 9- mixed result 10+ Success
Automatic Victory Rule
If the difference between the modifiers of the two sides is 4 or greater, the side with the higher modifier automatically wins.