Percentiles & Bell Curves

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schoon schoon's picture
Percentiles & Bell Curves
I have a question about the theory behind your system choice that may be slightly esoteric.

Percentile systems tend to reflect a very linear probability curve, so while your chances of success increase with a better number, the chances of success in any one endeavor with modifiers follows a linear path.

Other systems that use 2 or 3 dice for rolls have a bell-shaped probability curve, which establishes average (the center part of the curve) and exceptional (the edges) areas of probability.

In my opinion "reality" tends to follow a bell curve, and thus provides a better simulation. Granted, "better simulation" is not absolutely necessary in a game, but I like it personally.

So my real question is: how did you look at probability curves for this system?
Decivre Decivre's picture
I think the game's main focus
I think the game's main focus is simplicity in gameplay. To me, Eclipse Phase's game engine sounds like it's three shakes from a universal game system... one of the reasons that my group and I have decided to design our own setting for the game. In that sense, linear probabilities tend to serve for simplicity far better than bell curves do... it simplifies the value of bonuses for the purpose of balance, as well as simplifying how to calculate the probability of success for those who don't know the math behind probability. It makes the game feel like less of a simulation, but some feel that high degrees of simulation detracts from gameplay and a good story.
Transhumans will one day be the Luddites of the posthuman age. [url=]Help me get my gaming fix, if you want.[/url]
RobBoyle RobBoyle's picture
This was one of the things we
This was one of the things we discussed when choosing a system, but it wasn't a game breaker for us. Simplicity was the primary goal, and one of the advantages of straight roll-under percentile systems is that it becomes very easy to eyeball the odds. Thus a gamemaster can fudge the modifiers and say to himself that he'll give that character an 80% chance of pulling an action off, so he tells the player to roll under an 80. It also gives players a better understanding of what they're getting when buying skills, etc.

Rob Boyle :: Posthuman Studios

schoon schoon's picture
Looks Good
Thank-you for the replies, Gentlemen.

I know that there are many ways to skin a game system (and that everyone thinks their way is the best!), and was just interested in the concepts behind those decisions.

Over the years I've tended to move towards more simple (though not simplistic) systems that don't get in the way of the story, so I'm heartened by the answers thus far.
Admini Admini's picture
Speaking as a DM, the

Speaking as a DM, the simplification in eyeballing is a major perk for me.