One particular game system mechanic that has been around since almost the beginning of role playing games is the percentile system, i.e. everything is on a scale of 1-100, and percentile dice is used to resolve tasks. Either two d10’s are rolled with one picked as the tens die, or a single hundred-sided die (uncommon, but not unheard of), and you usually must roll equal to or lower than the difficulty rating.
Pretty simple on the surface. It’s easy to understand that you’ve got a 43% chance of climbing that cliff. Percentile systems, in my experience, are more often used in SciFi games, but they also appear in all the different genres.
The problem arises when it comes to basic attributes. Since they usually are percentile only systems that don’t use any other scales or die types, a character’s basic attributes are usually also rated on a scale of 1-100. Unfortunately, there’s cap built into those numbers… 100. Nothing can go above 100. Otherwise how on Earth do you roll higher? Sure, you can use modifiers to bring down the target number, or you can artificially place a limit of 99, with any roll of 100 (double zero’s on those d10’s) being an automatic failure, but that feels and is artificial and unrealistic.
What I’ve come to call the Silverback Paradox (originally paradigm) is a ridiculous situation that highlights what I think is a problem with percentile systems.
Let’s say that you are about to start playing a contemporary, espionage-ish RPG that your friend Steve (everyone has a friend named Steve) is about to GM. Your character concept is of a former heavy-weight boxer turned spy. You initially roll a Physical Strength of 80, and use various background stuff to pump your strength up to a pretty bad-ass 95. So then let’s say that this character later on in the game finds himself tromping through the jungles of Peru hot on the trail of enemy agents.
RREEEAAAARRRGGGGG! A huge, full-grown silverback gorilla, disturbed by your presence near his family, bursts from the jungle, beats his chest to show his dominance, and then attacks.
What do you suppose the Physical Strength rating of that 9 foot mass of pissed off muscle is? It can’t be higher than 100, right? So if it’s at the maximum of 100, then that means his strength is only 5 points higher than yours?
That’s crap.
And that’s the crux of the problem. Percentile systems don’t scale up. I’ve seen a few examples of old-school systems that try to solve the problem by limiting the starting attribute ratings to around 70. That doesn’t work, though. It’s an artificial limit.
Now, I’ve seen the light of a solution to this, but it involves borrowing from a different game. What if you had an attribute scale that was open ended? What if attribute ratings modified your roll, instead of being an inherent target number?
I’ve attempted lately to use the d20 range of 3-18 for stats, with the modifier being increments of +5 instead of +1. For example, in d20, a Dexterity of 16 has a modifier of +3 (right? I don’t have my book on hand…). In this conversion, that rating would have a modifier of +15 to a percentile roll (or -15 if it’s roll-below instead of roll-higher).
I don’t know if that sounds good to you. Try it with Top Secret/S.I. (the best version of that game) and see if it works for you. It did for me.
There’s other ways of getting around that problem, and I’m sure out there somewhere is a game designer right now trying to use the percentile system in a new way that works for him or her.
I once had the idea of a percentile/percentile scale, but I couldn’t work out the numbers. With this scale, humans do indeed have attributes on a scale of 1-100, but that scale is number 30 on a meta-scale of 1-100. That gorilla would have a rating of 60, but his scale is at the 50 range. That probably doesn’t make sense… I’m still trying to figure it out, like I said. If I ever do get these numbers right, I feel like it’s the system I was born to design.
Once again I hope you liked my rambling. Let me know if you have any input/suggestions/criticisms.
Dice Mechanic 