Celebrim
Legend
Well, in theory you don't need classes, but classless systems often have problems with balance.
I personally don't think the really interesting number is the minimum number of classes a system can have and still be a good system, but rather the maximum number it can support and still be considered a well designed system.
And personally I'd put that number at generously 'less than 20'.
At some point you end up having mechanical variation rather than actual thematic variation. Too much mechanical variation for its own sake tends to result in duplicated effort, unnecessary complexity, and unexpected interactions and one or more classes that do the same thing needs to be culled in favor of the superior mechanic. You need to start asking yourself, "Is it really necessary to have a separate mechanic to do this or can I reuse an existing mechanic to do the same thing?"
An example of this would be GURPS. GURPS may be generic, but its subsystems aren't balanced with each other. So it has a magic subsystem that's largely designed to be balanced with swinging a sword. It also has a psionic subsystem that's largely designed to be balanced with firing a gun. So, there are justifications for both subsystems, but there never really is a justification for using both. In theory, everything that one can do, the other can do, and the big difference is basically in how many points the options cost. If you throw psionics into S&S GURPS game, you get a guy that use his mind as an effective machine gun rather than use magic as an effective crossbow. If you throw your psion into a GURPS super's game, then a whole new set of assumptions have to be considered.
When D&D first introduced Psionics, the whole point of the system was that it differed from the usual magic systems in that it wasn't tied to level. A 1st level character could be a powerful psionic. That was different and novel and perhaps justified a separate subsystem. But in later editions, this effective and notable difference was lost, and as a result psionics ended up just being a second totally redundant magical system.
Also, if you have more than 20 classes, chances are is that the problem you have is that your classes are too narrow, too inflexible, and too poorly thought out. Chances are, if you have more than 20 classes, you could usefully combine two or more classes and rather than reducing flexibility and customization options you'd actually be gaining them.
Finally, if you are finding that you have more than 20 classes, chances are you'd get more of what you want by converting some or all of your classes to a flexible class creation system where the player can mix and match options to obtain the class or character he wants. The only reason to have a system with 20 or more classes is to kill more trees so you can sell more books to players.
Prestige classes in particular annoy me. They are horrid design. 95% of them are pointless, and the remainder aren't actually class options as they are ways to subtly change the assumptions of the game with regard to its balance. Virtually every prestige class that is ever actually taken ammounts to a base class with more bonus feats/level and a fixed or nearly fixed progression of abilities. This isn't more flexibility, it's less flexibility. If you really wanted a feat every two levels or every level, you should just do that from the start and stop mucking around with things. Under my rules, "you don't take a prestige class, you become one" (to quote one of my players). There is no reason why anyone should be shunted into anything as narrow as a prestige class.
I personally don't think the really interesting number is the minimum number of classes a system can have and still be a good system, but rather the maximum number it can support and still be considered a well designed system.
And personally I'd put that number at generously 'less than 20'.
At some point you end up having mechanical variation rather than actual thematic variation. Too much mechanical variation for its own sake tends to result in duplicated effort, unnecessary complexity, and unexpected interactions and one or more classes that do the same thing needs to be culled in favor of the superior mechanic. You need to start asking yourself, "Is it really necessary to have a separate mechanic to do this or can I reuse an existing mechanic to do the same thing?"
An example of this would be GURPS. GURPS may be generic, but its subsystems aren't balanced with each other. So it has a magic subsystem that's largely designed to be balanced with swinging a sword. It also has a psionic subsystem that's largely designed to be balanced with firing a gun. So, there are justifications for both subsystems, but there never really is a justification for using both. In theory, everything that one can do, the other can do, and the big difference is basically in how many points the options cost. If you throw psionics into S&S GURPS game, you get a guy that use his mind as an effective machine gun rather than use magic as an effective crossbow. If you throw your psion into a GURPS super's game, then a whole new set of assumptions have to be considered.
When D&D first introduced Psionics, the whole point of the system was that it differed from the usual magic systems in that it wasn't tied to level. A 1st level character could be a powerful psionic. That was different and novel and perhaps justified a separate subsystem. But in later editions, this effective and notable difference was lost, and as a result psionics ended up just being a second totally redundant magical system.
Also, if you have more than 20 classes, chances are is that the problem you have is that your classes are too narrow, too inflexible, and too poorly thought out. Chances are, if you have more than 20 classes, you could usefully combine two or more classes and rather than reducing flexibility and customization options you'd actually be gaining them.
Finally, if you are finding that you have more than 20 classes, chances are you'd get more of what you want by converting some or all of your classes to a flexible class creation system where the player can mix and match options to obtain the class or character he wants. The only reason to have a system with 20 or more classes is to kill more trees so you can sell more books to players.
Prestige classes in particular annoy me. They are horrid design. 95% of them are pointless, and the remainder aren't actually class options as they are ways to subtly change the assumptions of the game with regard to its balance. Virtually every prestige class that is ever actually taken ammounts to a base class with more bonus feats/level and a fixed or nearly fixed progression of abilities. This isn't more flexibility, it's less flexibility. If you really wanted a feat every two levels or every level, you should just do that from the start and stop mucking around with things. Under my rules, "you don't take a prestige class, you become one" (to quote one of my players). There is no reason why anyone should be shunted into anything as narrow as a prestige class.
