Cervantes wrote:I have been thinking about how you'd end up running percentile roll-under in a way that doesn't end up being comedy of errors.
You basically can't. The advantage of d% roll-under is that it;s intuitively obvious what your chance to succeed is - your modified skill percentage
is your success percentage. So congratulations, if you have a 95% modified skill, you have a 95% chance of success. The problem of course, is that as we see from various attempts at fumbles rules in D&D, that even a 5% of total failure is fucking low comedy.
The next issue is the jumping problem. We don't care about the question "Can your character jump?" because the answer in most cases is simply an uninteresting "Yes." The actual question we are asking is "How far can the character jump?" and while you can restate it into a question that a percentage of failure makes sense for as "Can your character jump far enough?" you're still back to the problem that a jump slightly farther than your normal jump should be about 50% and a jump slightly shorter than your normal jump should be close to 100%. But our system has to give us those numbers for two different characters whose normal jumps are very different.
Simply put, there's a reasonably narrow area where success and failure should be reasonably equal in probability for a lot of tasks. And for tasks that are substantially easier or more difficult than the ones that are about equally likely to succeed or fail should just always or almost always succeed or fail.
D% Roll-Under is great at telling you what the chances are, but it's fucking worthless in setting up those chances in the first place. Scaling difficulties and task modifiers just don't fucking work at all for this.
-Username17