What happens if a DLL is missing at runtime?
The .NET Framework has a very advanced method of keeping track of the DLLs an application needs and knows how to find them at load time. If a DLL is simply missing, the application will continue to execute as long as the DLL is not needed.
Once a class from that DLL is needed, though, the application will provide an error saying it cannot load the DLL. To demonstrate this, rename one of the DLLs you built in this hour's project and run the application.