In order to get a context in a Windows App using CSOM, you still need to create a context. In C# with CSOM, you'd use:
using Microsoft.SharePoint.Client;
ClientContext cc = new ClientContext(Settings.Default.SiteName);
cc.AuthenticationMode = ClientAuthenticationMode.Default;
string username = Settings.Default.UserName;
string password = Settings.Default.Password;
string domain = Settings.Default.Domain;
NetworkCredential credentials = new NetworkCredential(username, password, domain);
cc.Credentials = credentials;
//Get a reference to the Web
Web web = cc.Web;
//pass a parameter to get a list...
List sourceList = web.Lists.GetByTitle(list);
cc.Load<List>(sourceList);
//...or hardcode the list name...
List products = web.Lists.GetByTitle("Items");
cc.Load<List>(products);
If don't get a context this way, you don't have a Context, Site or Web to reference with the CSOM nor the actual data.
You can use REST to access the data, but you still end up having to reference the site.
One more note: as a Windows App, not using CSOM, if you attempt to use the client Object model you will get a NULL for SPContext if you try to read it directly...because once again, you don't HAVE a Context, so you get a null.