UFO Game

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PlayerController : MonoBehaviour {

    public float speed;       //Floating point variable to store the player's movement speed.

    private Rigidbody2D rb2d;     //Store a reference to the Rigidbody2D component required to use 2D Physics

    void Start()
    {
        rb2d = GetComponent<Rigidbody2D> (); //Get and store a reference to the Rigidbody2D component so that we can access it.
    }

    void FixedUpdate()  //FixedUpdate is called at a fixed interval and is independent of frame rate. Put physics code here.
    {
        float moveHorizontal = Input.GetAxis ("Horizontal"); //Store the current horizontal input in the float moveHorizontal.
        float moveVertical = Input.GetAxis("Vertical");
        //grabs the input from player thru keyboard; float var moves hor/ver and record the hor/ver axis by keyboard


        Vector2 movement = new Vector2 (moveHorizontal, moveVertical);
        //Use the two store floats to create a new Vector2 variable movement.

        rb2d.AddForce (movement * speed);
        //Call the AddForce function of our Rigidbody2D rb2d supplying movement multiplied by speed to move our player.
    }

    void OnTriggerEnter2D(Collider2D other) //OnTriggerEnter2D is called whenever this object overlaps with a trigger collider.
    {
        if (other.gameObject.CompareTag("PickUp")) //Check the provided Collider2D parameter other to see if it is tagged "PickUp", if it is...
        {
                    other.gameObject.SetActive(false);