I've been playing through the Blood and Wine expansion for The Witcher 3 (excellent game, I highly recommend it), which is partly the reason the posts from be have trailed off of late. As it commonly happens, as I'm playing through Geralt of Rivia's world, I've started thinking about running a gothic horror/adventure game. While I love Geralt's world, I would make some changes.
First off, I'd likely use Savage Worlds for the system. It's simply become my go-to game for most genres these days.
I would change the general historic age to that of Colonial times. I recently watched The Witch and the idea of running a game in that time period, one in which I have largely ignored intrigues me. However, since +Sean Bircher hasn't released The King is Dead yet, I'm going to have to lean more on Rippers for mechanical material even though it takes place in a later, slightly more advanced time period.
The world will be dark and foreboding. I don't know that I'd have any other race playable other than humans, but if I did elves, dwarves, and like would have to be "roughed off" a bit to make them less Tolkien and more fitting to the mood of the setting. Likewise, the creatures would be of a darker bent. Fewer fairies and brownies and dragons, and more undead, more demons, and more generally nastier creatures.
Thankfully, there is a lot of inspiration out there for just such a game. The Colonial Gothic game material would be robbed from generously. Wizards of the Coast's Innistrad setting for Magic the Gathering is right up the alley that I want to wander down. Of course Rippers, and Sean's Wine and Savages blog would be heavily referenced as well.
Much like other settings I've pondered, I doubt I'll ever really get around to making anything of my own. I'll likely just wait for The King is Dead to be released, honestly. Still, a lot of the fun of this hobby is the dreaming up of a setting and putting the wheels in motion...even if they tend to fall off rather quickly...