The dice system I’m working on for both my WIP games is a 2d10 system that takes hints from d20 and Blades in the Dark, among others. I call it Dios because it’s d10s, get it? I kill me.
The main idea is that you roll 2d10 and add them up, compare against a DC. If you have more skill and/or favorable conditions, you add dice. If you have unfavorable conditions you subtract dice. if you end up with more than 2 dice, you roll them all and choose the two highest. If you end up with only 1 die to roll, you roll 3d10 and take the lowest 2, if you end up with no dice to roll, you roll 4d10 take the lowest 2. Skills get ranks of 1-4, where the rank is the number of dice you start with in your pool.
I think attributes are going to add small bonuses to rolls (0-3), but haven’t entirely decided that part yet.
Why use 2d10? It lets me use d20-like DCs, which are familiar to many people, and allow the GM and the game to be flexible about difficulties (this is a problem I have with Blades and PbtA). But it also gives the rolls a curve, so your rolls cluster around average much more often (in fact 28% of rolls are 10, 11, or 12).
It also lets me use an advantage-like mechanic of rolling extra dice and choosing the highest, but with a smaller impact than advantage gives you in D&D. An extra die is sorta like +3, which is a big deal in the middle of the curve, but less so on the outsides. For example, 3d10, choose the two highest looks like this:
The midpoint of the curve moves from 11 to 14. I like that this helps a lot in the middle of the curve – you’re much less likely to fail at everyday tasks – but really difficult stuff is still pretty tough. Getting an 18+ is 6% with 2d10, but still only 14% with 3d10.
Unlike 5e’s advantage, Dios lets you roll multiple extra d10s, since each one is really only like half of 5e’s advantage, and none of them screw up the curve the way d20’s does (seriously, look at this craziness:
I’m still tweaking Dios, but I think this is a really good start.