OP, check out the Fabled Lands gamebook series (there's a fan-made Java app which has the six books currently published of the planned 12-book series, which also nicely handles all the bookkeeping). It doesn't solve your "interesting combat" problem, but it is the only case I know of where traditional IF (paper books, no less!) has done a truly open world RPG.
You can for instance become a sailing merchant just by buying a boat and trading at the various ports. Or you can pursue various quests. I ended up being a street ruffian because I found a loop that involved me getting jumped in an alley and beating my attackers which was surprisingly lucrative and repeatable.
There are also some quests which actually change the state of the world (this is done in a book by having you write a word on your character sheet and then directing you to different sections depending on the words you have on your sheet).
You can for instance become a sailing merchant just by buying a boat and trading at the various ports. Or you can pursue various quests. I ended up being a street ruffian because I found a loop that involved me getting jumped in an alley and beating my attackers which was surprisingly lucrative and repeatable.
There are also some quests which actually change the state of the world (this is done in a book by having you write a word on your character sheet and then directing you to different sections depending on the words you have on your sheet).