Countdown Timer

I am trying to make a game where you have 3 seconds to shoot a moving alien that keeps respawning. I want it to be that when I shoot it it sets the time back to 3 seconds so I have 3 seconds to try and shoot it again and e.t.c until I dont manage to shoot it in 3 seconds and I lose. I have everything in place except the timer script that I want to countdown showing seconds and milliseconds. Could you please try to make this script countdown from a number instead of up from 0?

using UnityEngine;
using UnityEngine.UI;
using TMPro;

public class Timer : MonoBehaviour
public TextMeshProUGUI timerText;
public bool playing;
public float timer;

void Update()
    if (playing == true)
        timer += Time.deltaTime;
        UpdateText(timer, timerText);

void UpdateText(float t, TextMeshProUGUI text)
    int seconds =- Mathf.FloorToInt(t % 60f);
    int milliseconds =- Mathf.FloorToInt((t * 100f) % 100f);
    text.text = seconds.ToString("00") + "." + milliseconds.ToString("0");


I’d use a coroutine for this. Have a property (boolean) to indicate if times up or not. Every time you want to start the 3 second timer, call the public method “StartTimer” - It will safely stop and start a new timer. In your Update method, monitor the timesUp property … If it goes true, time is up!

public bool timesUp = false;

public void StartTimer() 

private IEnumerator StopWatchCR()
    timesUp = false;
    yield return new WaitForSeconds(3);
    timesUp = true;

You can replace the mess inside of UpdateText with a call to ToString

timerText.text = timer.ToString("F"))