Platformer Walkthrough @ NYU (Code from https://unity3d.com/learn/tutorials/topics/2d-game-creation/creating-basic-platformer-game)

Getting-Started.md

• Make a Unity Account/Download and install Unity (https://accounts.unity3d.com/sign-up)
• Download "2D Platformer" from asset store https://www.assetstore.unity3d.com/en/#!/content/11228
• Download "2D Pack" from asset store https://www.assetstore.unity3d.com/en/#!/content/73728

PickupCoin.cs

using UnityEngine;
using System.Collections;

public class PickupCoin : MonoBehaviour {

    // Use this for initialization
    void Start () {
    
    }
    
    // Update is called once per frame
    void Update () {
    
    }

    void OnTriggerEnter2D (Collider2D other)
    {
        if (other.gameObject.CompareTag("Player"))
            Destroy(gameObject);
    }
}

SimplePlatformController.cs

using UnityEngine;
using System.Collections;

public class SimplePlatformController : MonoBehaviour {

    [HideInInspector] public bool facingRight = true;
    [HideInInspector] public bool jump = false;
    public float moveForce = 365f;
    public float maxSpeed = 5f;
    public float jumpForce = 1000f;
    public Transform groundCheck;


    private bool grounded = false;
    private Animator anim;
    private Rigidbody2D rb2d;


    // Use this for initialization
    void Awake () 
    {
        anim = GetComponent<Animator>();
        rb2d = GetComponent<Rigidbody2D>();
    }
    
    // Update is called once per frame
    void Update () 
    {
        grounded = Physics2D.Linecast(transform.position, groundCheck.position, 1 << LayerMask.NameToLayer("Ground"));

        if (Input.GetButtonDown("Jump") && grounded)
        {
            jump = true;
        }
    }

    void FixedUpdate()
    {
        float h = Input.GetAxis("Horizontal");

        anim.SetFloat("Speed", Mathf.Abs(h));

        if (h * rb2d.velocity.x < maxSpeed)
            rb2d.AddForce(Vector2.right * h * moveForce);

        if (Mathf.Abs (rb2d.velocity.x) > maxSpeed)
            rb2d.velocity = new Vector2(Mathf.Sign (rb2d.velocity.x) * maxSpeed, rb2d.velocity.y);

        if (h > 0 && !facingRight)
            Flip ();
        else if (h < 0 && facingRight)
            Flip ();

        if (jump)
        {
            anim.SetTrigger("Jump");
            rb2d.AddForce(new Vector2(0f, jumpForce));
            jump = false;
        }
    }


    void Flip()
    {
        facingRight = !facingRight;
        Vector3 theScale = transform.localScale;
        theScale.x *= -1;
        transform.localScale = theScale;
    }
}

SpawnCoins.cs

using UnityEngine;
using System.Collections;

public class SpawnCoins : MonoBehaviour {

    public Transform[] coinSpawns;
    public GameObject coin;

    // Use this for initialization
    void Start () {
    
        Spawn();
    }

    void Spawn()
    {
        for (int i = 0; i < coinSpawns.Length; i++)
        {
            int coinFlip = Random.Range (0, 2);
            if (coinFlip > 0)
                Instantiate(coin, coinSpawns[i].position, Quaternion.identity);
        }
    }

}

SpawnPlatforms.cs

using UnityEngine;
using System.Collections;

public class SpawnPlatforms : MonoBehaviour {

    public int maxPlatforms = 20;
    public GameObject platform;
    public float horizontalMin = 7.5f;
    public float horizontalMax = 14f;
    public float verticalMin = -6f;
    public float verticalMax = 6;


    private Vector2 originPosition;


    void Start () {

        originPosition = transform.position;
        Spawn ();
    
    }

    void Spawn()
    {
        for (int i = 0; i < maxPlatforms; i++)
        {
            Vector2 randomPosition = originPosition + new Vector2 (Random.Range(horizontalMin, horizontalMax), Random.Range (verticalMin, verticalMax));
            Instantiate(platform, randomPosition, Quaternion.identity);
            originPosition = randomPosition;
        }
    }

}