The instructions
here should be mostly up to date. The main gotcha is that I use Visual Studio 2013 (haven't upgraded yet). If you don't have it, I think you can still get the express version (the free one)
here, but I'm not sure.
Also, it's important to note that there isn't a single master solution file. I was building it from the ground up one module at a time. You can look at the various "testbeds" in some of the solutions. But they may or may not actually be buildable and running currently. Slipstream.Testbed, if it's working, is probably the most interesting thing to build and run, as it simulates some simple fluid physics. I have a "bot testbed" I'm working on now, but it's not really ready to look at or checked in yet.
I haven't been good at keeping the binaries in the bin/release up to date, so you'll need to probably rebuild everything using the batch file in Scripts/BuildAll-Release.bat. You'll need to run it a few times, most likely, because it doesn't know anything about dependencies and just builds things more or less in alphabetical order.
I've generally tried to keep the repository up to date, but I have a lot of minor changes on my local client that are only half finished, so I'm not sure if in the current state it's in it will actually build and run. But I think it should.