My Big Book of Ideas
Some ideas for a proposed 2d10 Pathfinder. Replace all instances of 1d20 with 2d10.
*Stats matter much more; rolls will tend to the average, meaning a stat difference can have a huge impact.
*Slight skew towards higher results, since it is no longer possible to roll a 1. The average also slightly skews upwards. On the other hand, high roll results become very rare.
*New average roll: 11. Under d20, it’s 10.5.
There are two basic approaches:
1. The 2d10 rule applies only to skill checks and ability checks. Under this rule, there’s no need to instance special rules for very high and very low rolls, since these already do nothing.
2. The 2d10 rule applies to all rolls. In this case, it becomes necessary to instate some special rules for the effects that occur on a “natural” roll of the die.
Any special effect occurring on a natural roll of 20 now occurs on a natural roll where both dice show 9 or higher. This has a 4% probability, fairly close to the 5% probability of a 20. A special effect occurring on a natural roll of 19 or higher now occurs if both dice show 8 or higher, which is 9%, fairly close to the original probability. Special effects occurring on 18 or below now occur on a natural roll where both dice roll 7 or higher.
Below this, matters get a little more complicated. Natural 17 is represented in 2d10 when one die rolls 6 or higher, the other rolls 7 or higher. Natural 16 occurs if both dice show 6 or higher. Natural 15, finally, occurs when one die shows 6 or higher, the other shows 5 or higher.
This system overall makes critical hits a little more rare, on the level of a percent or so.
For low rolls: A special effect occurring on a natural roll of 1 occurs if both dice show 2 or lower. A special effect occurring on a natural roll of 2 occurs if both dice show 3 or lower. And so on.