Comment by Karliss
10 hours ago
The point of percentile dice isn't to generate a string between "0%" and "100%", it is to test if action with chance of x% success gets done or not. For every o value of x, there are x out of 100 values which are strictly less than x, or if you count 0 as 100 then there are x out of 100 values which are less than or equal to x. Either way you get x% percent chance for event to happen. If the dice had 101 sides, the probabilities would be x/101 which aren't nice round percents.
It even works correctly for 0% and 100% chance events. Assuming 0 is counted as 0 - For 0% there are 0 numbers less than 0 on dice so chance of throwing number less that is 0/100=0%. For 100% all 100 numbers are less than 100 so no matter what the result of throw is you will succeed.
Not necessarily "done or not" because it's narratively unsatisfying to just "fail". Imagine you watch a heist movie and in the last 20 minutes the gang are like "Stealing the master key to make a copy was vital to our plan but we failed" and they disband and that's the end of the movie. Realistic but not satisfying and the dice are for a game, a fiction, so we can just eliminate that unsatisfying result.
Modern systems tend to come up with some more interesting consequences, so e.g. maybe success is the thing the player wanted to do succeeds as they expected, but failure shades from "Small snag" to "Technically it did work, but..." like from "The target's PA, Betty, noticed you take the key, so now you also need to bribe Betty" through "Our copy won't actually work, we're going to need to keep the original and hope the copy fools them for long enough"
Or maybe we have a timing adjustment, success means that you pilfer the key, duplicate it in five minutes like planned and slip it back, mild failure is it takes a half hour and everybody will need to improvise for those extra minutes, and bad failure is you'll need it all night, change your plans to accommodate that.
The usual RPG response to the failed critical skill check is that the party just slaughters everyone in the casino instead.