SoyBoyController.cs

[RequireComponent(typeof(SpriteRenderer),typeof(Rigidbody2D),typeof(Animator))]

public float speed = 14f;
public float accel = 6f;
private Vector2 input;
private SpriteRenderer sr;
private Rigidbody2D rb;
private Animator animator;

sr = GetComponent<SpriteRenderer> ();
animator = GetComponent<Animator> ();
rb = GetComponent<Rigidbody2D> ();

input.x = Input.GetAxis ("Horizontal");
input.y = Input.GetAxis ("Jump");
if (input.x > 0f) {
	sr.flipX = false;
} else if (input.x <0f){
	sr.flipX = true;
}

var acceleration = accel;
var xVelocity = 0f;
if (input.x == 0) {
	xVelocity = 0f;
} else {
	xVelocity = rb.velocity.x;
}
rb.AddForce (new Vector2 (((input.x * speed) - rb.velocity.x) * acceleration, 0));
rb.velocity = new Vector2 (xVelocity, rb.velocity.y);