Been a while. 'Bout time I did another one of these.
So I've talked a whole lot about D&D on this blog and a whole little about any other system. Exalted, my favorite system (until recently) has been mentioned several times, but in general it's been in passing, or in comparison to D&D. I feel like this is a little unrepresentative of my tastes as a gamer. I know more about D&D than I do about any other system, but that's because it's an extraordinarily simple system to wrap your head around. What you see is what you get. Roll dice. Add number. Subtract target number. If result > 0, you win!
This is called a "static die" system. It's one die roll + one static number, checked against a target number (difficulty class or "DC" in D&D, though armor class also counts). This means that, due to the dice used, you have exactly a 5% chance to automatically succeed and a 5% chance to automatically fail. It doesn't matter if you've never touched a lockpick in your life there's a 5% chance that you will crack the masterpiece of the most esteemed locksmith in the world. Whether or not you have been an professional acrobat since you were old enough to do a cartwheel, there's a 5% chance that you won't be able to do a forward somersault without screwing up and spraining a muscle. Every time you try.
I've discussed this with people who were skeptical about this weird probability system and how painfully unrepresentative of actual skill it is (hello Eva!), and to that I're right. You're absolutely right. 5% is way too much leeway for instant success or humiliating failure. To make matters worse, in D&D, modifiers extremely swingy. +4 to hit is a pathetic number, while a +20 modifier (very easy to achieve by magic) is more important than the actual die roll. Skill is completely inconsistent in a static die system.
There is an alternative, and this is where we get into games I actually enjoy. The games I really really really want to play whenever I get a chance.
White Wolf is the most venerable example of something called the "success system." They probably invented it, hell if I know. In the ancient, respected tabletop RPG "Vampire: The Masquerade," your character's skill is not represented by a static number to be added to a single die roll. Instead, it is represented by a pool of dice to be rolled all at once. The sum of this roll doesn't matter, but the numbers on individual die faces do. On a ten-sided die, any result of 6 or higher is treated as a "success." All successes are then counted together to determine the degree of success you achieved.
It sounds complicated and mathy, and that's because it is. The end result, though, is that the average IS THE AVERAGE. Static dice are huge and swingy. There's a 5% chance to achieve any degree of variance, from horrible failure to mediocrity to miraculous success. The success system heavily favors the middle of the bell curve. Even in Exalted, a system known for throwing 15-20 dice at a time, results never tend to be more than two successes off of the median.
For players, this means that, in general, your character's chance at success at a given task is almost directly reliant on the difference between your character's skill and the difficulty of the task. Boom. Accurate representation of ability. There are still moments of resounding success or crippling failure, but it's not nearly as frequent as with a static die system, which means it's more reflective of real life. Throw 15d6 and count 5's and 6's, and you'll average 5 successes. Not every time, but most of the time by far, and variations tend to be 4 or 6 successes, not everything from 2 to 9.
I'm a gamer, and specifically a gameist. I tend to respect crunch, math, and mechanics much more than most of the people I play with. For me, then, it's important that the basic mechanics of a system be reliable. The d20 system is not that. Please don't be fooled by all of my D&D talk on this blog. It's a venerated and seasoned game, but given the choice, I'd rather play something a bit less...clumsy.
Exalted is was my one true love.
Then I found Shadowrun. More on that later.
TL;DR - There are realistic ways of displaying a character's skills and exactly none of them are found in D&D. Play Exalted.