OK, just downloaded and checked out the latest in the MG.Extended source.
But, as it uses NuGet for all the related packages, you can't "open" the solution for the first time offline as NuGet needs to restore the dependant packages.
Best thing to do is after you have cloned it, open it straight away and build the solution in the "Source" folder. This will recover the dependencies for the solution automatically (assuming you are using VS2013 with NuGet installed, or VS2015, any version will do)
Once built, simply right click the demo you want to run and set it as the "Startup project" or do Right-click on the project and select "Debug -> Start new instance"
I've noticed there are a few warnings and I've messaged the author about it, but you can safely ignore them and the demos still run fine.