I've got an idea, spawned from Uncharted and Indiana Jones mixed with fantasy.

Basically, my sarcastic/smooth treasure hunter gets a lead at some ruins. While he's probing the history of those ancient people, he finds a little stone trinket which acts as a key to a set of double doors. These lead to stairs, which eventually spiral downward for an hour or two like a tower before he opens it up to find... Another world? Indeed, the tower reaches up past the sky and into the former ruins, but all my guy can think about is the gold littered around the place. He quickly grasps that the famous treasure must be in this world somewhere and he isn't leaving without it....

He centures out to find your char, a high ranking person in one of the two civilized tribes of this world. There's the humans and the beastmen(nekos/kitsunes/ect). Aside from them, there's the Daemon tribe(spelled like that exactly), which is basically a name for all the horrors that roam the night. Basically she finds that he has the key and a prophecy that tells the 'keybearer' will rid the Daemons from this world.

It's going to start out low tech, but as we go you'll see that the treasure... Well, let's just say it's a lot more advanced than anything on earth.

I need a demale, anyone? It'll probably be mature....