I am trying to get a campaign going. It will be set in Greyhawk, but a modified version of the setting. For one thing many of the non human races will be fey in origin, the Dwarves, Elves and Gnomes were all originally fey, but eventually became more man-like. Halflings on the other hand are still considered demihumans, and there are additional demihuman races like troglodytes, no longer lizard-like, but instead a race of subterranean demihumans, and merfolk, which are obviously marine demihumans. I'm also rearranging the goblin races, hobgoblins are a smaller variety, rather than a larger one and the larger variety are called orcs, rather than having orcs and goblins be separate varieties. Goblins do vary by environment, as there are the more agile lowland orcs, and the stronger mountain orcs, as well as deep orcs. There are also crossbreeds of course, I'm thinking of making kobolds a crossbreed of gnome and goblin. Gnolls are in fact descended from orcs "blessed" by the demon lord Yeenoghu to resemble the canines that many goblins favor. Trolls also have changed as in my campaign they come in many varieties including ogres, and one resembling the traditional D&D troll. "Hill giants" for instance are a variety of troll. Goblins and trolls seemingly are related to certain varieties of evil fey, like the boggards and fomors respectively for instance. I am also using a version of Blackmoor closer to Dave Arneson's which also in a different place.
Now as for the campaign it's going to mostly be a sandbox, but there will also be a sort of plot, or at very least a theme. That being the Cult of Elemental Evil. Thus I will be using modules like the Village of Homlett/Temple of Elemental Evil, and the Giants/Drow series. These modules will not necessarily be as written. I'm considering heavily modify the Temple of Elemental Evil to address some complaints I've heard about it, for instance. I'm also using B2, and probably modifying the Caves of Chaos. I won't be using Queen of the Demonweb Pits.