2D Character Controller for Unity

2D Platformer is a type of game where the player jumps between platforms, avoids obstacles, and fights enemies, all of which is observed from a 2D side-view perspective.

To make a 2D Platformer Character Controller in Unity, follow the steps below.

The controller will be physics-based and will use a Rigidbody2D component.

Steps

• Open Scene with your 2D level (make sure the level sprites have 2D colliders attached, so the player won't fall through)
• Create a new GameObject and call it "Player"
• Create another GameObject, call it "player_sprite" and add the Sprite Renderer component to it
• Assign your sprite to "player_sprite" and move it inside the "Player" Object

• Create a new script, name it "CharacterController2D" and paste the code below inside it:

CharacterController2D.cs

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

[RequireComponent(typeof(Rigidbody2D))]
[RequireComponent(typeof(CapsuleCollider2D))]

public class CharacterController2D : MonoBehaviour
{
    // Move player in 2D space
    public float maxSpeed = 3.4f;
    public float jumpHeight = 6.5f;
    public float gravityScale = 1.5f;
    public Camera mainCamera;

    bool facingRight = true;
    float moveDirection = 0;
    bool isGrounded = false;
    Vector3 cameraPos;
    Rigidbody2D r2d;
    CapsuleCollider2D mainCollider;
    Transform t;

    // Use this for initialization
    void Start()
    {
        t = transform;
        r2d = GetComponent<Rigidbody2D>();
        mainCollider = GetComponent<CapsuleCollider2D>();
        r2d.freezeRotation = true;
        r2d.collisionDetectionMode = CollisionDetectionMode2D.Continuous;
        r2d.gravityScale = gravityScale;
        facingRight = t.localScale.x > 0;

        if (mainCamera)
        {
            cameraPos = mainCamera.transform.position;
        }
    }

    // Update is called once per frame
    void Update()
    {
        // Movement controls
        if ((Input.GetKey(KeyCode.A) || Input.GetKey(KeyCode.D)) && (isGrounded || Mathf.Abs(r2d.velocity.x) > 0.01f))
        {
            moveDirection = Input.GetKey(KeyCode.A) ? -1 : 1;
        }
        else
        {
            if (isGrounded || r2d.velocity.magnitude < 0.01f)
            {
                moveDirection = 0;
            }
        }

        // Change facing direction
        if (moveDirection != 0)
        {
            if (moveDirection > 0 && !facingRight)
            {
                facingRight = true;
                t.localScale = new Vector3(Mathf.Abs(t.localScale.x), t.localScale.y, transform.localScale.z);
            }
            if (moveDirection < 0 && facingRight)
            {
                facingRight = false;
                t.localScale = new Vector3(-Mathf.Abs(t.localScale.x), t.localScale.y, t.localScale.z);
            }
        }

        // Jumping
        if (Input.GetKeyDown(KeyCode.W) && isGrounded)
        {
            r2d.velocity = new Vector2(r2d.velocity.x, jumpHeight);
        }

        // Camera follow
        if (mainCamera)
        {
            mainCamera.transform.position = new Vector3(t.position.x, cameraPos.y, cameraPos.z);
        }
    }

    void FixedUpdate()
    {
        Bounds colliderBounds = mainCollider.bounds;
        float colliderRadius = mainCollider.size.x * 0.4f * Mathf.Abs(transform.localScale.x);
        Vector3 groundCheckPos = colliderBounds.min + new Vector3(colliderBounds.size.x * 0.5f, colliderRadius * 0.9f, 0);
        // Check if player is grounded
        Collider2D[] colliders = Physics2D.OverlapCircleAll(groundCheckPos, colliderRadius);
        //Check if any of the overlapping colliders are not player collider, if so, set isGrounded to true
        isGrounded = false;
        if (colliders.Length > 0)
        {
            for (int i = 0; i < colliders.Length; i++)
            {
                if (colliders[i] != mainCollider)
                {
                    isGrounded = true;
                    break;
                }
            }
        }

        // Apply movement velocity
        r2d.velocity = new Vector2((moveDirection) * maxSpeed, r2d.velocity.y);

        // Simple debug
        Debug.DrawLine(groundCheckPos, groundCheckPos - new Vector3(0, colliderRadius, 0), isGrounded ? Color.green : Color.red);
        Debug.DrawLine(groundCheckPos, groundCheckPos - new Vector3(colliderRadius, 0, 0), isGrounded ? Color.green : Color.red);
    }
}

• Attach the CharacterController2D script to the "Player" Object (You'll notice it also added other components called Rigidbody2D and CapsuleCollider2D)
• Tweak CapsuleCollider2D dimensions until they match the player Sprite
• Make sure there are no child colliders and the CapsuleCollider2D is the only collider attached to this player

In the CharacterController2D script there's an option to assign the Main Camera variable which can be any Camera that'll follow the player:

The 2D Character Controller is now ready!