text code to unlock door 2D

Create an InputField and attach a script that checks the text.

In the InputField's OnEndEdit, add the script's text check function.

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;
 
 public class InputFieldKeywords : MonoBehaviour {
 
     InputField inputField;
 
     // Use this for initialization
     void Awake () {
         inputField = GetComponent<InputField>();
     }
 
     public void CheckText()
     {
         if (inputField.text == "open")
         {
             Debug.Log("door open");
             // TODO unlock door
         }
     }
 }

Unity Manual - UI

Unity Tutorials - UI