What I want in my next fantasy RPG campaign. Characters that do more character related stuff or more accurately have a greater focus on a class feature. Fighters that have give the player more decisions than get as much armor as possible and the weapon with the best damage rating. Magic-Users that have to fuss with magical things other folks don't seem to deal with. Clerics that deal with their faith and the supernatural more often then simply turning undead and bashing demons. Thieves that empower players that want to make decisions other than when to roll dice.
I suspect each of these is going to require a campaign specific subset of rules or mini-game.
Fighters can be expanded by the fighter having to learn different fighting stance and the tactics and special moves that go along with each so the subset of rules here is a bit more fiddly creation and advancement choices that on first blush don't seem to0 different from feats and skills. The clever player of a fighter should be able to learn to ask what stance his opponents are using and deploy their skills to counter and take advantage of their foes skills not just roll as high as they can with the dice.
Magic-Users have a number of subsystems that have been present in D&D and related games since it's inception that are seldom explored with any depth. Magic item creation offers a lot of ground for the player of the Magic-User to discover and employ a body of lure so as to discover the formulas for magical inks and potions along with patterns for glyphs/runes. Magic-Users may also have to track and balance magical energies to empower their spells and provide an edge in magical contests by delving into what energies foes have invested in.
Clerics have a relationship with a faith or deity that could really be expanded on to better refine and define their access to spells and special abilities. This relationship shouldn't just be front loaded it should be active and require maintenance on the part of the cleric to maintain their powers. All but the smallest of mythological pantheons has a host of supernatural entities clerics can learn to interact with to gain favor(s) and lore.
Thieves can be expanded by putting bit more focus into breaking and entering and other tasks of the trade. I've touched on alternate lock-picking resolution in the past and feel expansion in this area will add more to the role of thieves as burglars by expanding the vocabulary and range of tasks that can be involved in cracking those locks. A thieves relationships with contacts and fences can also serve to give the class more depth within a campaign.
Just an overview of areas I've been exploring in my notes that I wish to embody in my campaigns. Some of the ideas I have touched on before on this blog and all of them will be getting more attention here.