First RPG game. What helps you choose a game design direction?

What I would like to see is a roleplaying game with a really innovative combat/ability check system, that acts as a board game. Just adjusting a dice roll after referencing some charts doesn't seem to take enough strategy to make it fun for me. The role playing (character development) and story aspect of an RPG are great, but most games seem to make the GAME aspect really thin ( Parcheesi has more strategy than most). I do enjoy the GURPS combat system as it can be used as almost a stand alone game, but it can get bogged down in minutia, and trying to streamline it can unbalance it.

GAME aspect I'd like to see in an RPG:

1) Reward for good roleplaying; such as getting to draw from a special deck which can aid you later.

2) More strategy than just your skill versus your enemy's armor (and skill). Abstracting it into deciding what to do based on what combination of cards (or whatever) you happen to have (based on your character) may actually make the character feel more real, like they have some tendencies of their own.

3) Flexibility enough that whatever creative monster you come up with ( Descent doesn't allow this), you can come up with their hand, method of operation, etc, to have an interesting and fierce battle, where you as the GM don't have to pull any punches.

If this exists, somebody tell me. If it doesn't Torsk, you will be my hero if you invent it.

My suggestion would be to grow outwards from the combat and leveling mechanics you already have.
How do you handle movement in combat? Can you use that same map system for the overworld?
How do you handle events in combats: randomly or GMed? You could probably expand these mechanics to cover overworld events as well.

In terms of making it a board game that can be expanded to larger campaigns it might be worthwhile to look at something like Gamma World: the character creation/ setup is hugely compressed compared to the 4ED D&D it is based on. While you can later build upon the mechanical base as much as you'd like, the barrier to entry is low: you basically just draw 2 origins and make up a quick explanation of how they fit together.

If you want storytelling/ roleplaying to be a major component of your game you probably want to have more open-ended mechanics, for instance more levels of success (perfect/success/success with penalty/failure with bonus/failure/SNAFU vs success/failure). This will also tend to push you towards a more GM route for adjudication. If you're handing out rewards for roleplaying you might want to keep them more open-ended than specific cards, like Hero points that you can spend to do epic actions, because they will allow these players more opportunities to do more awesome roleplaying. Or, as your leveling system is so central to your design, reward them through that system and bring the focus back on your beautiful core mechanics (Synergy!). Still, for a lot of players roleplaying is its own reward: in Gloom you don't get any mechanical reward for storytelling, but it makes the game significantly better than playing it silent.

I put all the potential game directions for an RPG into an events table and roll a D100 percentile dice.

Then I add any potential modifiers and let the result determine the games fate.

In the event of a bad direction I have full confidence in my ability to make saving throws with my 'lucky' dice.