Add project files.

Class1.cs

+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Mastermind
+{
+    internal class Class1
+    {
+    }
+}

Mastermind.csproj

+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

Mastermind.sln

+
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 17
+VisualStudioVersion = 17.11.35312.102
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Mastermind", "Mastermind.csproj", "{0C91672B-2686-4DE6-B700-EB6BE6EF6981}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{0C91672B-2686-4DE6-B700-EB6BE6EF6981}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{0C91672B-2686-4DE6-B700-EB6BE6EF6981}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{0C91672B-2686-4DE6-B700-EB6BE6EF6981}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{0C91672B-2686-4DE6-B700-EB6BE6EF6981}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {5E81EC89-5A0F-432B-A684-54DAD3077CAF}
+	EndGlobalSection
+EndGlobal

Program.cs

+using System;
+
+namespace Program
+{
+    class Program
+    {
+        static void Main()
+        {
+
+        } 
+    }
+}
\ No newline at end of file