Demon_打砖块（建造一面墙，发射子弹打砖块）

using UnityEngine;
using System.Collections;

public class CubeInit : MonoBehaviour {

    //砖块预设体
    public GameObject cubePrefab;
    //砖墙宽高
    public Vector2 W_H = new Vector2(8,8);

    void Start()
    {
        for (int i = 0; i < W_H.x; i++) {
            for (int j = 0; j < W_H.y; j++) {
                //砖块位置
                Vector3 pos = new Vector3 (i,j,0);
                //生成砖块
                Instantiate (cubePrefab, pos, Quaternion.identity);
            }
        }
    }

}

要发射的子弹预设体

using UnityEngine;
using System.Collections;

public class Fire : MonoBehaviour {

    //子弹预设体
    public GameObject bulletPrefab;
    //子弹飞行速度
    public float speed = 3f;
    //鼠标转换的射线
    private Ray mouseRay;
    //射线碰撞检测器
    private RaycastHit hit;

    void Update()
    {
        //按下鼠标左键
        if (Input.GetMouseButtonDown (0)) {
            //获取射线对象
            mouseRay = Camera.main.ScreenPointToRay (Input.mousePosition);
            //如果射线检测到碰撞体
            if (Physics.Raycast (mouseRay, out hit)) {
                //生成子弹
                GameObject currentBullet = Instantiate (bulletPrefab, 
                    Camera.main.transform.position,
                    Quaternion.identity) as GameObject;
                //子弹飞行方向
                Vector3 dir = hit.point - Camera.main.transform.position;
                //给子弹施加一个力
                currentBullet.GetComponent<Rigidbody> ().AddForce (dir.normalized * speed);
                //2秒后销毁子弹
                Destroy (currentBullet, 2f);
            }
        }
    }
}