error CS0518: Predefined type 'System.Object' is not defined or imported

[TangoMarker]

I'm getting a lot of these errors when I try to run this solution. I'm using Windows 10 15063 and I have VS 2017 with Universal Windows package installed. Any ideas?

[NGame1]

You need w10 build 16299 and universal Windows platform sdk version 16299 or newer. I prefer to upgrade to 1803 (build 17134)