Solomon Dark takes place a couple months after Solomon's Boneyard. You can kinda figure out Boneyard being phased out, with Dark being the remake that supplants it.
You can actually explore the Wizard's College a bit-- it acts as the staging area like the town in Diablo. Perks, Inventory, and items are all managed here, plus there's some characters around just for talking to for fun.
The gameplay itself is virtually identical to Boneyard, except it has fleshed out skill trees like Diablo or Titan Quest (you can still play in random mode, but essentially, "Bribe Destiny" is unlocked from the start). There are more monsters, more spells, more items, more perks, and even set items. If everything goes well, there will also be some tools that will allow people to make their own graveyards (along with some simple event triggers) and upload them to the web for sharing (similarly to Kitty Connect in Robot Wants Kitty). I am not 100% positive that that's going to work out yet, but I'm trying.
You can follow progress on Youtube (http://www.youtube.com/watch?v=eX7m7...ture=g-all-lik), but I only upload videos when I hit a major milestone. The next upload I will do will be when the summoning skills are complete.