A couple of weeks ago I was working on the first module supplement for Chronicle, and thinking about the first exposure play test hall at Gen Con. I was statting out the mini bosses and thinking that at higher levels the attack roll was going to become meaningless and combat was always going to be decided by damage rolls, so what was really the point of armor.
That led me to thinking about how attack rolls work in the d20 system, because up till now Chronicle has used a light version of d20. But what works for a roll playing game is a little unsatisfying for a board game. For one thing it's a two step step process: roll to hit; roll for damage. If you flatten the attack bonus and armor class progressions, you also have to give characters a way to add bonuses back in to hit the really high level monsters...
Then I started thinking about armor and weapons. Armor, instead of being something to test against, could have a direct effect on the ability of weapons to do damage. If I switched from the d20 mechanic to a dice pool mechanic weapons could add dice to a general attack pool and armor could remove dice.
I had already settled on three sided dice (six sided dice with 1-3 on two sides each) as a way of randomizing bonuses of special abilities. Now I was looking at using the same dice, but as part of a pool instead of as a bonus. By capping the entire dice pool to 8 dice I could make the rolling manageable and by capping the dice that are kept to 4 I could make the math manageable. The new system becomes about managing probability, which is kind of what combat is all about. Plus you get to roll a handful of dice.
Dice codes were going to be a problem, writing things like 'roll 2 keep 1' is pretty inelegant, and probably confusing to non gamers. I already had white d3s and black d3s. In the old system the d3s were bonus dice, one color for characters and the other for monsters. Now black dice would be be used for weapons and armor: weapons add black dice and armor subtracts them. Black dice you keep. White dice are for skill, you can replace black dice with higher rolling white dice. 'Roll 2 keep 1' becomes roll 2 black and one white, or a black square with the number 2 and a white square with the number 1.
Then I added in red dice for magic. You keep red dice, but armor (black dice) can't take away red dice.
So in the new Fist Full of Dice Engine (TM) you max out at 12d3, of which you keep a maximum of 8. The combat roll is a direct comparison between your roll and your opponent's roll with the higher roll winning and the difference between the two rolls becoming the damage that the loser takes.
I've been converting all of the characters and cards to the new mechanic.