(on r/rpg, someone asks about multi-class leveling systems, and I took the opportunity to describe that of Pathfinder 2e; recording here for posterity…)

I'm looking for systems that let you progress multiple classes at the same time. Ones where you "multiclass" by hybridizing existing classes together as opposed to the usual DnD 3.5/5e way of simply dividing levels between multiple classes.

Pathfinder 2E.

Something a bit like 1E's Variant Multiclass rules is the core of the progression system.

Classes still have their "inherent" progression. There are not-player-selectable core elements of the class (A Rogue's Sneak Attack ability. A caster's spell-casting progression), though even those are customizable via what PF2 never quite calls "subclasses". ;)

But on top of that, character progression is arranged around player selection of Feats —- eg. Fighter Feats, Bard Feats. At every even level, players choose from a set of class-specific feats (and at every odd level, not-Class-specific feats). Many feats do have prerequisites … levels of course, other feats, subclass selection, ability/skill levels … but equally as many don't.

"Multiclassing" is not achieved by taking a level in a different class, but instead by taking a specific type of "Multiclass Archetype Dedication Feat". This usually grants a somewhat-neutered version of the class' main feature; for example, the Druid Dedication will offer a reduced spellcasting progression, and you need to choose an Order, and while you /do/ get a Skill thematically appropriate to the Order, you /don't/ get the Order's spell benefit (eg. goodberry or wild morph … though you can get those if you take another Feat :). The Archetype Dedication then unlocks a feat that lets you take a normal class Feat, again at a reduced level (eg. at 4th level you can take a 1st-or-2nd level Class Feat; at 6th level you can take a 3rd-or-4th level Class Feat, &c.).

On the whole, it's a pretty wonderful system, that allows a broad amount of player choice an allows effective and real "multi-classing" while eliminating the downsides associated with "the dip". The cost is complexity and "analysis paralysis" with a lot of player options at every level.

In the bog-standard rules, you get a class feat selection every even level, and you can choose from anything available to you either from your initial class, /or/ unlocked by one of these Archetype Dedications. With the very popular "Free Archetype" rules, you get basically two class feats at every even level, one from your Class "feat pool", /and/ one from your Archetype feat pool.

There are some opportunities for overlap, just because of the "primitive operations" all the feats – system-wide – are based on.

For example, I'm building a Magus / Investigator right now. The Investigator has a feat that would let me roll Recall Knowledge as a side effect of core class ability; the Magus has a feat that gives solid benefits for a critically-successful RK check (and to the rest of the party) any time it happens. And a third feat (that costs a (roughly per-encounter) "focus"-point) gives me "advantage" on the next RK check I make.

I'll note as well that there are Archetype Dedications that are /not/ multiclass, but more thematic, providing access to a coherent set of abilities … "Beastmaster", "Eldritch Archer", "Poisoner", "Scroll Trickster", "Marshal", "Linguist", &c. These are sort of "mixins" that let you tailor characters to your liking.