Unity3d Windows Store build won't open in Visual Studio

There was a time (about 6 months ago) where I had my system completely setup to port my Unity games to Windows Store. I'd build the game, open in visual studio, and wallah.

Recently I reformatted my hard drive and have installed my OS and programs fresh. Problem is that now I cannot get my Windows Store builds to even open in Visual Studio. I get an error message and then my project is marked as 'incompatible' with VS 2013. VS 2012 won't even let me run it without a software key. I honestly cannot remember which version of VS I was running when everything worked, but I'm almost certain I had tried VS 2013 with no luck and eventually got it working with 2012.

Again, it's been several months since I built a Windows Store app last, but I've noticed that my build settings in Unity have changed substantially, and that I was getting a lot of new errors when trying to build. I had to copy a lot of files between my two Win 8 SDK folders in order to even build the project successfully. Most notable is that I no longer have the two Direct3D build options when porting using the 8.1 SDK, I only get two XAML solutions.

Have I missed something, either with VS or Unity? If anyone could point me in the right direction I would really appreciate it. I have installed every Win 8/Phone SDK I can find. I've tried about 6 versions of VS (I don't remember there being so many options last time) and none of them will open my Windows Store builds.

I'd provide error messages, but there are a lot of different errors depending on which setup I use.