The code in UnitySamples-csharp is sort of the backend for the Unity samples applications. To run these applications, you need to start Unity and open the UnitySamples folder. This is probably not clear if you haven’t worked with Unity before, maybe we should clarify it more in the Developer’s Guide.
To test and run a graphical example that does not require Unity, check out the MonoSamples solution file that contains a Windows Forms project called GazeAwarePanels. As Anders said, we are working on a separate EyeX SDK for .NET which will be announced soon.