So it's been a bit over 24 hours since random inspiration struck and I came up with the idea for DICE the RPG. Let's see what actual concrete ideas have congealed since then...
So, the system basics would be based around a character's Core Dice, essentially a number of dice equal to your level, of the appropriate Dice Class. So for instance a 4th level d6 is a 4d6 and that's also his Core Dice. While a 1st level d12 would use 1d12 for her Core Dice.
Actions would involve a simple Target Number system, probably in units of 5, starting with 5 as the most basic and simple. Actions are resolved by rolling 1d20 and adding your Core Dice. So the 1st level d12 above would roll 1d20+1d12 when resolving most actions.
There are roughly 3 types of Actions: Brute, Skilled, and Esoteric. Brute actions are those that anyone can attempt without any training (although obviously skill makes success more likely). Skilled and Esoteric actions represent actions with significantly greater complexity. Dice making Skilled actions against unskilled targets (say sneaking past a guard, or using judo to flip an enemy over your shoulder) the target is denied their Core Dice on defense. So a 4d6 attempting a Skilled action against an unskilled 4d10 (say...sneaking past him) would roll 1d20+4d6 vs the d10's straight 1d20 roll. Likewise anyone attempting a Skilled action when unskilled (say if that same d10 wanted to sneak by someone) they only get to roll 1d20 to give it a try. Esoteric actions occupy a third tier that's even more exclusive. No one can attempt them at all without the appropriate Esoteric ability. Like Skilled Vs Unskilled actions, those attempting to defend against Esoteric Actions roll a straight d20.
Balance between different Dice will depend on the balance of skill vs unskilled vs esoteric actions.
-d12s can only perform Brute actions.
-d10s can select a single Talent at character creation representing a narrow area where they are Skilled (such as Perceptive or Sneaky).
-d8s can select a range of Talents (say 2-3) giving them several narrow or related areas of skill.
-d6s can select a broadly defined Profession (say Ninja or Con Artist) which defines a large area where they are skilled, as well as a small selection of Talents.
-d4s have automatic access to Esoteric abilities, allowing them to attempt a very broad range of actions (via magic, weird science, etc).
Each Dice Class may also has at least one automatic Skill. (say courage for d12s, Weapon mastery for d10s, willpower for d8s...etc).
Finally characters can be further customized through Knacks (or Edges or Feats or Advantages. Whatever you like) that provide individual special abilities or new Skilled or Esoteric abilities.
Obviously hideously rough and probably quite unbalanced so far. But certainly interesting.