Time for action – the basic flying saucer

To add a flying saucer to Mars Runner, perform the following steps:

1. 1. Add a new class file called EnemySaucer.cs to the Mars Runner project.

2. 2. Add the following using directives at the beginning of the EnemySaucer class file:

   using Microsoft.Xna.Framework;
   using Microsoft.Xna.Framework.Graphics;

3. 3. Modify the declaration of the EnemySaucer class to inherit from the GameEntity class. The new declaration should read as follows:

   class EnemySaucer : GameEntity

4. 4. Add a constructor for the EnemySaucer class as follows:

   #region Constructor
   public EnemySaucer(GraphicsDevice device, Model model, Vector3 position)
       : base(device, model, position)
   {
       scale = 0.0025f;
       yaw = MathHelper.ToRadians(180);
   }
   #endregion

5. 5. In the Fields region of the MarsRunnerPlayScreen class, add a new field for our enemy saucer as follows:

   EnemySaucer enemy;

6. 6. In the LoadContent() method of the MarsRunnerPlayScreen class, initialize enemy as follows:

   enemy = new EnemySaucer...