The Pool
A Milestone in RPG Design
The Pool is a little RPG document written by James V. West. While it may not look like much nowadays, at the time it was written it opened a lot of eyes.
The resolution mechanic is as simple as it is elegant. Roll some d6. If you rolled at least a single 1 then you succeed, otherwise you fail.
Using AnyDice, it's easy to compare the performance of different pool sizes. The transposed graph view is very useful for this:
loop DICE over {1..10} {
output DICE d (d6 = 1) > 0 named "[DICE]d"
}
And here it is in a table, along with a rough estimate mnemonic:
| Dice | Odds | Mnemonic |
|---|---|---|
| 1 | 16.67% | ⅙ |
| 2 | 30.56% | ⅓ |
| 3 | 42.13% | |
| 4 | 51.77% | ½ |
| 5 | 59.81% | |
| 6 | 66.51% | ⅔ |
| 7 | 72.09% | |
| 8 | 76.74% | ¾ |
| 9 | 80.62% | |
| 10 | 83.85% | ⅚ |