In the draft I have going for Saga of the Splintered Realm, I am using 'feats' as a catch all for a variety of ways you can upgrade your character. Characters earn feat 'slots' at advancement thresholds:
Humans earn feats at levels 3, 6, 9, 12
Demi-humans earn feats at levels 4, 8, 12
Feats include pretty much everything you could want to upgrade your character. Examples include:
- The ability to cast an extra level 1 spell. You could take this as a fighter to pick up cure light wounds, or as a magic user to get an extra level 1 spell slot.
- Enemy, giving you +1 to all rolls against that enemy type.
- A +1 to any one attribute score.
- An extra attack each round.
- Two-handed fighting
Right now, I know that these are not particularly well balanced, but I'm working towards a modicum of balance. Some feats seems more powerful than others (an extra attack each round trumps a level 1 spell pretty handily), so it's absolutely a work in progress. We play tested last night with a group of level 5 characters, and I'll walk you through how this worked out...
The human fighter and elf champion both took quick strike, giving the +1 attack roll every round (with the primary weapon). My human cleric took +1 vs. an enemy type (he selected undead), and this came in very handy against the vampire they squared off with. The human magic user took quick spell, granting one round of double-casting per turn.
I like this as a mechanic that unifies a variety of other abilities into one mechanic. You want to be a very quick ranged combatant? Take sharpshooting (giving you +2 to damage) and quick draw (giving you an extra missile weapon attack per round). Pick up expertise in DEX (taking your DEX to 13) and you are borderline Legolas... by the time you get to level 12.
I plan to layer every other ability into this hierarchy... so the fellowship found a bunch of roc eggs, and they plan to raise these. If they want to train them and take them as steeds, that's fine - but they are going to have to use a feat slot to pick up the ability to ride and handle a mount like that.
Feats provide a mechanical framework for a lot of the quirky things players want to be able to do, and sets up specific levels at which they can pick up such abilities.