Ilium said:
Treatments I've see (and worked on briefly) used d20 Modern as the base, and made all the magic skill and feat driven. That way you can have Strong hero wizards (Hagrid) Smart Hero wizards (Hermione) and Dedicated Hero wizards (Harry?)
That's exactly what we did for my homebrew. The six Basic Classes were just the d20Modern classes, tweaked slightly to be more D&Dish (no medium saves, no class defense bonus, some weapon/armor proficiencies, etc.), and you could unlock one of the three magical Advanced Classes as you went.
To unlock an Advanced Class, you had to take an Affinity feat. For instance, the WIS-based one:
Ritual Affinity:
req WIS 13, good Will save in a previous class/race
Benefit: gives about half of the cantrip-level ability of the Wizard class.
And then the Wizard class (which is a WIS-based Wizard/Cleric hybrid) simply requires the Feat to enter, meaning you can qualify after only a single Basic level, if you picked one with a good Will save. Since our spellcasting is somewhat skill-based, there's not much of a penalty if you want to take more Basic classes before entering.
Our other two affinities, Freeform and Innate, unlock the Channeler (INT-based psion-like class) and Mutant (CHA-based class with lots of innate bonuses and spell-like abilities) in similar ways.
(IMC, every race has 1-2 Racial Levels. The Human racial level allows you to pick one save to be Good for that level, which makes it easy to qualify for these Feats. If you don't do this, you could change the requirement to "+1 Base Will save", meaning the +1 must come from your classes, like BAB does.)
It's worked beautifully. A couple people never took an affinity. One of the fighter-types only took an affinity to get a few weak spell-like abilities, and then never entered its class, but most of the others took at least a couple levels of one of the classes. (Most of the non-Human races are LA+1 in our world, and most of them get one specific Affinity for free, so practically everyone has a little magical ability.)
The way I intend to do it, if I ever get around to it, is to make "Wizard/Witch" a feat you have to take at 1st level. You either are one or you're not. Then you could have Occupations like "Muggle-born" and "Pureblood" in addition to using some of the regular ones.
See, we did it the other way, because while the talent for magic is rare, we simply assumed that those people who'd join the party are those who had the talent, whether they took advantage of it or not. Sure, it's a bit too convenient, but we really disliked forcing players to decide whether they ever wanted magic or not at level 1. That's one of the things we loved the most about the jump to 3E; multiclassers could change their minds down the road.