Catching Squares

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Content;
using Microsoft.Xna.Framework.GamerServices;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework.Input;
using Microsoft.Xna.Framework.Media;

namespace Square_Chase
{
    /// <summary>
    /// This is the main type for your game
    /// </summary>
    public class Game1 : Microsoft.Xna.Framework.Game
    {
        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        public static extern uint MessageBox(IntPtr hWnd, String text, String caption, uint type);
        GraphicsDeviceManager graphics;
        SpriteBatch spriteBatch;
        Random rand=new Random();
        Texture2D squareTexture;
        Rectangle currentSquare;
        int playerScore = 0;
        float timeRemaining = 0.0f;
        const float TimePerSquare = 0.75f;
        Color[] colors = new Color[3] { Color.Red, Color.Green,Color.Blue };
        public Game1()
        {
            graphics = new GraphicsDeviceManager(this);
            Content.RootDirectory = "Content";
        }

        /// <summary>
        /// Allows the game to perform any initialization it needs to before starting to run.
        /// This is where it can query for any required services and load any non-graphic
        /// related content.  Calling base.Initialize will enumerate through any components
        /// and initialize them as well.
        /// </summary>
        protected override void Initialize()
        {
            // TODO: Add your initialization logic here
            this.IsMouseVisible = true;
            base.Initialize();
        }

        /// <summary>
        /// LoadContent will be called once per game and is the place to load
        /// all of your content.
        /// </summary>
        protected override void LoadContent()
        {
            // Create a new SpriteBatch, which can be used to draw textures.
            spriteBatch = new SpriteBatch(GraphicsDevice);
            squareTexture = Content.Load<Texture2D>(@"SQUARE");
            // TODO: use this.Content to load your game content here
        }

        /// <summary>
        /// UnloadContent will be called once per game and is the place to unload
        /// all content.
        /// </summary>
        protected override void UnloadContent()
        {
            // TODO: Unload any non ContentManager content here
        }

        /// <summary>
        /// Allows the game to run logic such as updating the world,
        /// checking for collisions, gathering input, and playing audio.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Update(GameTime gameTime)
        {
            // Allows the game to exit
            if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed)
                this.Exit();
            if (gameTime.TotalGameTime.TotalSeconds > 10)
            {
                int msg = playerScore;
                MessageBox(new IntPtr(0), Convert.ToString(msg), "Score", 0);
                this.Exit();
            }
            // TODO: Add your update logic here
            if (timeRemaining == 0.0f)
            {
                currentSquare = new Rectangle(
                rand.Next(0, this.Window.ClientBounds.Width - 25),
                rand.Next(0, this.Window.ClientBounds.Height - 25),
                25, 25);
                timeRemaining = TimePerSquare;
            }
            MouseState mouse = Mouse.GetState();
            if ((mouse.LeftButton == ButtonState.Pressed) &&
            (currentSquare.Contains(mouse.X, mouse.Y)))
            {
                playerScore++;
                timeRemaining = 0.0f;
            }
            timeRemaining = MathHelper.Max(0, timeRemaining -
            (float)gameTime.ElapsedGameTime.TotalSeconds);
            this.Window.Title = "Score : " + playerScore.ToString();
            base.Update(gameTime);
        }

        /// <summary>
        /// This is called when the game should draw itself.
        /// </summary>
        /// <param name="gameTime">Provides a snapshot of timing values.</param>
        protected override void Draw(GameTime gameTime)
        {
            GraphicsDevice.Clear(Color.CornflowerBlue);
            spriteBatch.Begin();
            spriteBatch.Draw(
            squareTexture,
            currentSquare,
            colors[playerScore % 3]);
            spriteBatch.End();
            // TODO: Add your drawing code here

            base.Draw(gameTime);
        }
    }
}