How can I add an offline map in a Windows forms application (C# .NET 8)?

Question

I use GMap.NET in the application I developed on a Windows form application. It works fine, but how can I make it work in an environment without internet?

(First of all, I'm sorry for my bad English, English is not my native language.)

I am trying to develop a simple application on Windows form application (C# .NET 8.0). I apologize for my inexperience as I am new to this field.

Below is the code of my application.

using GMap.NET;
using GMap.NET.MapProviders;
using GMap.NET.WindowsForms;
using System;
using System.Windows.Forms;

namespace harita_3_offline
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            /* Map Config */
            //gMapControl1.Dock = DockStyle.Fill;
            GMap.NET.GMaps.Instance.Mode = GMap.NET.AccessMode.ServerAndCache;
            gMapControl1.CacheLocation = @"D:\\cache\\turkey.mbtiles";
            gMapControl1.DragButton = MouseButtons.Left;
            gMapControl1.MapProvider = GMapProviders.GoogleMap;
            gMapControl1.Position = new GMap.NET.PointLatLng(37.87425528270441, 32.493648881146235);
          
            gMapControl1.MinZoom = 1;
            gMapControl1.MaxZoom = 20;
            gMapControl1.Zoom = 15;

            gMapControl1.ShowCenter = false;
            /* ./Map Config */
        }
    }
}

I have a map object named gMapControl1. There are a few customizations in my code.

My problem is, The map works fine when connected to the internet. But when I disconnect the internet, the map is corrupted and does not work.

I downloaded a ".mbtiles" file from the internet. This is how I added it to my application.

gMapControl1.CacheLocation = @"D:\\cache\\turkey.mbtiles";

But this didn't solve my problem. I did research on the internet. It says it can show the cached map. But what I want is to show the map of the entire country I downloaded. How can I do that?

I tried some solutions below but none of them worked :(

GreatMaps (GMap.net) Offline Files...To Download? I couldn't run the shared github application because it was old.

GMap .net offline Likewise, I could not manage to run it because the codes shared on github were too old.