unity timer with an int code example

Example 1: unity timer

float timeLeft = 30.0f;
     
     void Update()
     {
         timeLeft -= Time.deltaTime;
         if(timeLeft < 0)
         {
             GameOver();
         }
     }

Example 2: unity interval timer

public Rigidbody projectile;

void Start(){
  					//(methodname, timeUntilFirstCall, repeatTime)
	InvokeRepeating("LaunchProjectile", 2.0f, 0.3f); //time needs to be > 0
}

void LaunchProjectile(){
	Rigidbody instance = Instantiate(projectile);
	instance.velocity = Random.insideUnitSphere * 5;
}