Assume I want to have characters defined by classes, archetypes, whatever. And there’s no advancement, or at least sufficiently little advancement that the choices made at chargen always define the character.
But I want to have multiclassing. Or, more exactly, I want to have characters with differing numbers of archetypes without imbalancing them.
So a class/archetype can’t be a package of mostly or entirely good abilities, because adding another class makes a character better. Thus, the first idea I had was to have chargen start with an “average” set of traits, and each class adds a package of advantages and disadvantages. Works numerically, but I know that “disadvantages cost negative points” systems are easily exploitable. That is, players will try to put PCs in situations that take advantage of their strong points. Only if players and their characters had no control over the situation would “disadvantages cost negative points” be balanced. Thus, having more advantages and disadvantages is generally a good thing. I presume it’s for this reason that the Fate versions I’ve seen don’t just give you a pool of points but specify how many skills of what value you must buy in chargen.
So what other options are there?
I recognize that this post is about something very similar, but there’s no answer satisfying my requirements.
From the description, Apocalypse World and its derivatives allow for cross-class abilities, but only through experience rather than at chargen. Other suggestions lean toward full point-buy, but that’s not what I’m talking about. I don’t want complex character generation. And again, I don’t want to add abilities from other classes in play, but to have class combination in chargen.