Implementing a Bullet class
Next, we set up our Bullet prefab with two orthogonal planes and a box collider, using a laser-like material and a Particles/Additive-Layer property in the Shader field:
Figure 2.4 – Our Bullet prefab
The code in the Bullet.cs file is as follows:
using UnityEngine;
using System.Collections;
public class Bullet : MonoBehaviour {
    //Explosion Effect
    [SerializeField] // Used to expose in the inspector private
                    // fields!
    private GameObject Explosion;
    [SerializeField]
    private float Speed = 600.0f;
    [SerializeField]
    private float LifeTime = 3.0f;
    public int damage = 50;
    void Start() {
  ...
