MainWindow.xaml.cs

using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace AnimalsMatchGame
{
    using System.Windows.Threading;
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        DispatcherTimer timer = new DispatcherTimer();
        int tenthsOfSecondsElapsed;
        int matchesFound;

        public MainWindow()
        {
            InitializeComponent();

            timer.Interval = TimeSpan.FromSeconds(0.1);
            timer.Tick += Timer_Tick;

            SetUpGame();
        }

        private void Timer_Tick(object? sender, EventArgs e)
        {
            tenthsOfSecondsElapsed++;
            timeTextBlock.Text = (tenthsOfSecondsElapsed / 10F).ToString("0.0s");
            if (matchesFound == 8)
            {
                timer.Stop();
                timeTextBlock.Text = timeTextBlock.Text + " - Play again?";
            }
        }

        private void SetUpGame()
        {
            List<string> animalEmoji = new List<string>
            {
                "🐶", "🐶",
                "🐱", "🐱",
                "🐭", "🐭",
                "🐹", "🐹",
                "🐰", "🐰",
                "🦊", "🦊",
                "🐻", "🐻",
                "🐼", "🐼",
            };

            Random random = new Random();

            foreach (TextBlock textBlock in mainGrid.Children.OfType<TextBlock>())
            {
                if (textBlock.Name != "timeTextBlock")
                {
                    int index = random.Next(animalEmoji.Count);
                    string nextEmoji = animalEmoji[index];
                    textBlock.Text = nextEmoji;
                    animalEmoji.RemoveAt(index);
                }

                timer.Start();
                tenthsOfSecondsElapsed = 0;
                matchesFound = 0;
            }   
            
        }

        TextBlock lastTextBlockClicked;
        bool findingMatch = false;

        private void TextBlock_MouseDown(object sender, MouseButtonEventArgs e)
        {
            TextBlock textBlock = sender as TextBlock;

            if (findingMatch == false)
            {
                textBlock.Visibility = Visibility.Hidden;
                lastTextBlockClicked = textBlock;
                findingMatch = true;
            }
            else if (textBlock.Text == lastTextBlockClicked.Text)
            {
                matchesFound++;
                textBlock.Visibility = Visibility.Hidden;
                findingMatch = false;
            }
            else
            {
                lastTextBlockClicked.Visibility = Visibility.Visible;
                findingMatch = false;
            }

        }

        private void timeTextBlock_MouseDown(object sender, MouseButtonEventArgs e)
        {
            if(matchesFound == 8)
            {
                SetUpGame();
            }   
        }
    }
}