Here we have a mysterious island, secluded far from prying eyes and, if your heroes are unlucky enough to visit, far from help.
Let's answer the question we posed last time - what kind of maniac carves off the peak of a mountain and puts a French chateaux on top? To my mind, a dragon. A red dragon, because I'm a traditionalist.
From here, everything else falls into place. Why does this dragon keep up a "most dangerous game" charade? To increase his hoard. How does he do this? In the guise of a rich count. Why does he have a chateaux on top of a mountain? He's a DRAGON.
What kind of horrors live in the Howling Caverns, which honeycomb all across the island? Kobolds, who cover the island with primitive, painful, and nonlethal traps. Who loves in the Hollow village? A tribe of lizardfolk, who keep any and all guests on the island and sink any ship attempting to leave. What happened to the ruined tower? That was the tower of the wizard who lived here up until the dragon arrived.
I think that's enough setup; I encourage you all to have fun fitting this into your own games. I for one am probably going to do my best to actually make an adventure - maybe a campaign setting - all for this island!