So, I'm working on my own RPG, based on my own urban-fantasy IP I call Nightmares in the Dark (
http://www.nightmaresinthedark.com/).
The basics of the setting are that it's the modern world as we know, but with a hidden underworld of elves, dwarves, goblins, trolls, vampires, werewolves, demons, dragons, and more. Magic is a real force, with a good deal of pseudo-scientific background to explain it. Magic is driven by spirits in a parallel dimensional space, who live off the energies generated by thought and emotion, and are able to return some of that energy to our dimension, in the form of magical effects. We can communicate with them through altered states and rituals, and they can be bound to people or objects to perform magic on command. Your soul is another kind of spirit, and can be 'awakened' to learn how to perform magic as well, but it carries consequences, in the form of deviations, magical mutations which confer some of the nature of the magic you're trying to perform, often in the form of animal-like aspects. Stack these changes up over time in a magic-using community, and you wind up with the other magical races. Go too far with these changes, and you lose control of yourself to your instincts, and become a monster.
Mechanically and conceptually, I take influences from D&D 3.5e and 4e, d20 Modern (including Urban Arcana), the new World of Darkness (including specifically Werewolf, Changeling, and several of the core offbooks like Mirrors, Changing Breeds, and Second Sight), as well as the Dresden Files RPG. (I'll note similar concepts for reference from those.)
So my core mechanic is 3d6 with exploding 6s, used for attacks, defenses, skill checks, and so on. The other standard sizes of dice are used as well, mostly for damage and health expressions. XP is a high-value resource for character advancement, often granted one point at a time, but continuously throughout a given session rather than just at the end. XP can be spent on the fly to buy character traits, or 'burned' temporarily to provide boosts to current actions or extend your resources, and recovered on the next rest.
Six core stats for characters, tweaked from the d20 standard: Strength, Agility, Endurance, Intellect, Charisma, Resolve. (Presently I use the d20-style "10 as +0 average" modifier system, but aside from wanting a derived bonus from the score, I could set that +0 point anywhere. I could even invert the system and use the mod as the base and derive a 'score' for special uses.) Strength for melee and archery damage and movement/carry capacity. Agility for one component of all physical attack rolls (explained below), and the Dodge defense (one of my core three defense forms, see below). Endurance for health and the Tough defense. Intellect for skill points and damage with guns and spells. Charisma for all 'special' in-combat rolls (explained below), and Energy points, one of the major resources for getting things done. Resolve for the Initiative check (rolled every round), the Wealth rating, and the Will defense.
The system has five main bonuses granted by levels. (I use d20-style classes, referred to as Archetypes, with multiclassing encouraged. Each archetype is mainly one primary character concept, in a non-exclusive manner. I'll run them down below.)
The first two are the Combat and Special bonuses. The Combat bonus is used for all physical attacks (the Agil modifier is
always added), but is tempered by the attack's related skill. Presently I have 4 such skills, with associated ability: Archery (Res), Brawling (End), Firearms (Res), & Weaponry (Str), though I'm still fiddling with which and what. To make a standard attack, use the
lesser of either the Combat+Agl or Skill+mod. Likewise, when using some other skill in combat, generally you would use the Special+Cha or the skill+mod, whichever is lower, to make a base check. (Just about every skill has special actions you can do which don't use the standard basic skill check, changing things up. I'm still working out the specifics, with either every skill granting special utility powers/maneuvers on certain ranks, or those powers are cheaply purchasable once you have that rank prerequisite.)
The other three bonuses are defensive, Dodge, Tough, and Will. Conceptually similar to Fort/Ref/Will from d20/D&D, but more fundamental. Dodge is your overall avoidance check, akin to AC/touch-AC. Tough is checked for stability/footing and general hardiness checks (though not poisons), but mainly used as an intrinsic damage resistance (this damage is made less lethal, rather than eliminated). Will is fairly basic, mental resistance, but also used vs social effects. The big kicker of Will is twofold, one, that you have a secondary number called a Feral Instinct, which is added for external Will checks, but that you have to roll
against in particular circumstances. Two, Will is used for resisting Deviations, and a too weakly-willed character will suffer for it.
The two main resource points are Health and Energy. You have the base amount granted at character creation, but each archetype level grants you one Health and Energy die, which are recuperative (sort of like healing surges in 4e), allowing you to recover naturally. (there are also natural and magical healing and energy sources. Natural ones, like Leader abilities, recharge your dice, while magical healing is an independent number, operating outside the level-dice system.)
Health has three forms, Vital, Lethal, and Blunt, and you get your Endurance score of each. (This is similar to the WoD's Aggravated/Lethal/Bashing types, or the D&D-style lethal/nonlethal split, with the -10 under 0 similar to the Vital/Aggravated set) The Tough defense above, and armor, reduces damage by one rating, so 5 lethal damage, if you've got a Tough of 3, is received as 2 lethal damage and 3 blunt. Excess damage of one kind rolls over into the next. (Blunt damage is more akin to Bludgeoning damage than Nonlethal, to make a d20 comparison.)
Energy loosely defined as not just physical energy, but also motivation and personal drive. You get points equal to your Charisma score, and it can be spent to boost actions, including boosting physical attacks and social actions. (it's akin to 4e psionics at-wills, you can always use the attack, but spending extra points strengthens the effect.) Magic can be powered by spending energy directly, or you can invoke emotions to generate Eos and Nyx energy, which are constructive and destructive, respectively, and spend more efficiently than straight Energy.
Not sure what the char limit on posts is here, going to post this then reserve a few replies for more info.