public void RandomChoose() //Chossing a random cube { System.Random r1 = new System.Random(); System.Random r2 = new System.Random(); int row = r1.Next(0, grid.GetLength(0)); int column = r2.Next(0, grid.GetLength(1)); var value = grid[row, column]; Debug.Log("choose a random block"); previousRedCude = value.GetComponent <GridItem>(); previousRedCude.ChangeToRed(); StartTime = 0f; //reset the start time to 0 }