Huh. It's funny this comes up. I'm working on making my own entry for the
Great Conjunction RPG Design Contest, and number of attributes is definitely something I've been thinking about.
I decided to keep the number of attributes down. My theory is long, and I'll just put it in Sblocks so that anyone who doesn't care, doesn't need to read it:
[sblock=Wik's Attribute Theory]
Alright. So, in old RPGs (read as: OD&D era), Attributes were not really balanced. The game really gave more benefits to physical attributes over mental attributes, and it could be argued it still does today. However, this was fine with old editions of D&D, for a fairly simple reason - the game assumed random generation of attributes.
Since you applied a random number to each attribute (remember, earlier games had a "roll in order" as the base assumption), it didn't matter if Strength was better than Intelligence - both were determined randomly. If attribute A (Strength) is going to be used ten times more than Attribute B (Physical Appearance)... who cares?
Because attributes were randomly generated, and not balanced roughly against one another, you could afford to have numerous attributes. This is the approach used in games like the Palladium RPG, for example, where Speed (a small burst to your land speed) and Physical Beauty (A bonus few ever applied) are not nearly as important as, say, I.Q. (which adds a flat bonus on all skill checks).
When you have a point-based approach, though, you need to make sure all the attributes are roughly equal - if Strength is twice as good as physical beauty, than it really only encourages a bunch of ugly fighters. So, the way to balance the attributes in the end is to cut them down to a smaller number, because the fewers numbers and variables there are to crunch, the easier it is to work out balance issues.
[/sblock]
So, I'm using a non-random attribute generation system, and I figured on only four very broad attributes - Body, Intelligence, Agility, and Spirit (the BIAS system!)
Body is your strength, endurance, muscle, health, resistance to disease, and whatnot.
Agility is hand-eye co-ordination, flexibility, and really anything relating to grace and refined movement.
Intelligence is brain power, knowledge base, and personal ingeniuty.
Spirit is force of will, perception, charisma, and even a bit of luck.
Since players only have four numbers to divvy among the attributes (-10%, +0%, +10%, and +20%), there are some tough decisions to be made - which I think is necessary in any RPG.
