Para la creación de personajes NPC’s te dejamos como ejemplo el siguiente código. Utilízalo como guía para practicar.

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

public class NPCMovement : MonoBehaviour
{
/**** Variables. ****/

public float npcSpeed = 1.5f;
public bool isWalking;
public float walkTime = 1.5f;
public float waitTime = 3.0f;

private float waitTimeCounter;
private float walkCounter;
private int currentDirection;

/**** Components. ****/

private Vector2[] walkingDirections =
{
    //Definimos las diferentes direcciones que tomará nuestro npc.
    new Vector2(1,0),
    new Vector2(0,1),
    new Vector2(-1,0),
    new Vector2(0, -1)
};

private Rigidbody2D npcRigidbody;


/**** Metudus. ****/

// Start is called before the first frame update
void Start()
{
    npcRigidbody = GetComponent<Rigidbody2D>();
    waitTimeCounter = waitTime;
    walkCounter = walkTime;
}

// Update is called once per frame
void Update()
{
    if (isWalking)
    {
        npcRigidbody.velocity = walkingDirections[currentDirection] * npcSpeed;
        walkCounter -= Time.deltaTime;
        if (walkCounter < 0)
        {
            StopWalking();
        }
    }
    else
    {
        npcRigidbody.velocity = Vector2.zero;
        waitTimeCounter -= Time.deltaTime;

        if (waitTimeCounter < 0)
        {
            StartWalking();
        }
    }
}

private void StartWalking()
{
    isWalking = true;
    currentDirection = Random.Range(0, 4);
    walkCounter = walkTime;
}

private void StopWalking()
{
    isWalking = false;
    waitTimeCounter = waitTime;
    npcRigidbody.velocity = Vector2.zero;
}
}**