Having issue with Bindable value in XAML page

I have code that is a sample bowling recap where 3 games are entered and are summarized in a Series column. The problem that I am experiencing is the Series column is not getting updated as I anticipate. Obviously, I am doing something wrong but can not see what I am doing wrong. Below is the code that supports the application:

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="HoriView.MainPage">
    
    <StackLayout>
        <ScrollView>
            <VerticalStackLayout
                Spacing="25"
                Padding="30,0"
                VerticalOptions="Center">

                <Image
                    Source="dotnet_bot.png"
                    HeightRequest="200"
                    HorizontalOptions="Center" />
    
                <Label
                    Text="Hello, Bowlers!"
                    FontSize="32"
                    HorizontalOptions="Center" />
    
                <Label
                    Text="Bowling Recap Snippet"
                    FontSize="18"
                    HorizontalOptions="Center" />
    
            </VerticalStackLayout>
    
        </ScrollView>
        <ScrollView>
            <HorizontalStackLayout HorizontalOptions="Center">
                <CollectionView SelectionMode="Single" ItemsSource="{Binding scores}" ItemsLayout="HorizontalList">
                    <CollectionView.ItemTemplate>
                        <DataTemplate>
                            <Grid Padding="10">
                                <Grid.RowDefinitions>
                                    <RowDefinition Height="Auto"/>
                                    <RowDefinition Height="Auto"/>
                                    <RowDefinition Height="Auto"/>
                                    <RowDefinition Height="Auto"/>
                                </Grid.RowDefinitions>
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition Width="Auto"/>
                                </Grid.ColumnDefinitions>
                                <Label Text="{Binding Game}" FontSize="Medium" WidthRequest="83" VerticalOptions="Center" HorizontalOptions="EndAndExpand" HorizontalTextAlignment="End"></Label>
                               <Entry Grid.Row="1" Text="{Binding Score}" TextChanged="UpdateGame" Keyboard="Numeric" ReturnType="Next" Placeholder="Game" WidthRequest="83" FontSize="Medium" ></Entry>
                            </Grid>
                        </DataTemplate>
                    </CollectionView.ItemTemplate>
                </CollectionView>
            </HorizontalStackLayout>
        </ScrollView>
    </StackLayout>
    
</ContentPage>

using System.Collections.ObjectModel;
    
namespace HoriView;
    
public partial class MainPage : ContentPage
{
    public ObservableCollection<Games> scores { get; set; }
    string header = "Game";
    
    public MainPage()
    {
    	InitializeComponent();
        scores= new ObservableCollection<Games>();
        for(int i=0; i<4; i++)
    	{
    		if (i == 3)
    		{
    			header = "Series";
    		}
    		else
    		{
    			header = "Game" + (i+1).ToString();
    		}
    		scores.Add(new Games() 
    		{ 
    			Game=header, 
    			Score=0
    		});
                
    	}
        BindingContext = this;
    }
    
    public void UpdateGame(object sender, TextChangedEventArgs e)
    {
    	scores[scores.Count-1].Score = 0;
    	for(int i=0; i< scores.Count-1; i++) 
    	{
            scores[scores.Count - 1].Score += scores[i].Score;
        }
    }
}

public class Games
{
    public string Game { get; set; }
    public int Score { get; set; }
}

Any help would be appreciated. Thanks.

Your Games class doesn't implement the INotifyPropertyChanged interface.

You can either implement that manually:

public class Games : INotifyPropertyChanged
{
    private string _game;
    public string Game
    {
        get => _game;
        set
        {
            if(_game == value) return;
            _game = value;
            OnPropertyChanged();
        }
    }

    private int _score;
    public int Score
    {
        get => _score;
        set
        {
            if(_score == value) return;
            _score = value;
            OnPropertyChanged();
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    private void OnPropertyChanged([CallerMemberName] string propertyName = "")  
    {  
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }  
}

Alternatively, you could also inherit from ObservableObject from the MVVM Community Toolkit and then simply write the following using Source Generators:

public partial class Games : ObservableObject
{
    [ObservableProperty]
    private string _game;

    [ObservableProperty]
    private int _score;
}

In this case, you only define the backing fields and the Source Generators will create the uppercase, observable properties Game and Score for you.