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Monday, 3 February 2014

Alternative Dice Pool for Fate Core

An alternative dice pool mechanic for Fate Core

I've been noodling around with a d12 dice pool system which has languished in an unpublished, untested homebrew for more than a year and realised only this morning that the scaling I came up with matches up exactly against the ladder in Fate Core. Here's the Fate ladder with the dice pools against it.

expanded fate core ladder

In what I hope will be a peanut butter vs. chocolate moment I've revisited it here fusing the original mechanics with Fate Core. This will be playtested it in my upcoming post-human Fate game, The Signal which you can follow here on the blog.
Reading the dice

Using this system all tests are opposed whether actively by another character or passively by the challenge rating of the situation.

Each party rolls a number of d12 and whichever has the highest result on a single die succeeds. If more than one of your dice is higher than your opponent's best roll then you

Here's a couple of examples:
Jake and Sam are arm wrestling to settle a bet. 
Jake's skill is Good (4d12).
Sam's is Average (2d12).

Their results are:
Jake - 3, 8, 9, 10
Sam - 4, 11

Sam has the highest result (11) and slowly forces Jake's arm to
the table.

Jake demands best of three and in the next round:

Jake - 2, 6, 9, 11
Sam - 3, 5

Jake has the highest result (11) and also has two other results
higher than Sam's best score.

It's a clear victory for Jake as he slams Sam's arm down.

In the examples above, there's clearly a narrative difference between the two results. Mechanically in Fate that's a boost. In this system you gain a boost if two or more dice beat your opponent's highest roll.

What happens if it's a draw?

In the case of a draw the acting character gains a boost over the reacting character. A draw means that you've not managed to create an advantage, overcome an obstacle or score a hit in combat.
Boosts, Invokes and Fate Points

There are some deviations from vanilla Fate Core here but much of the mechanic remains the same.

You get a boost when:

  • Two or more dice beat your opponent's highest roll

  • You are the acting character and the dice roll is a draw

  • The text of a skill or stunt allows you to.

Invoking an aspect (or boost):

  • Grants +2 to a single die after it has been rolled

  • Allows you to roll an additional die

  • Allows you to re-roll some or all of your dice

Fate points are used to activate aspects, stunts etc. as per the core rules.
Dice Options

Using a dice pool opens up other ways of modifying likely outcomes and handling the effects of gear, stunts and status effects.

  • Add or subtract a value to one or more dice

  • Add or remove whole dice

  • Cap number of successes

So why d12?

For a number of reasons, some more subjective than others. Firstly the maths for the d12 is more elegant than the d10; it is divisible by 1, 2, 3, 4, 6 and 12. Additionally it also divides neatly into 60. It's also an underused polyhedral compared to the d20 (which introduces too much variability) or d10. It also rolls well and has a nice aesthetic shape.
And what about the probabilities?

The only way to really test this was a monte-carlo simulation. You can find the link below. The most interesting thing to note is that in evenly matched contests the more skilled the protagonists are the more likely the result is to be a draw. This supports the narrative often seen in film and in books where a contest between two masters takes longer than the same conflict between novices. Not shown are the asymmetric tests, however as expected whoever rolls the most dice has a better chance of coming out on top.

Check out the results here.