Help with a Simple game code

You could flash the lights:

void setup()
{
  pinMode(Player1ButtonPin, INPUT_PULLUP);
  pinMode(Player1RelayPin, OUTPUT);

  pinMode(Player2ButtonPin, INPUT_PULLUP);
  pinMode(Player2RelayPin, OUTPUT);

  // Signal for attention.  Blink both lights three times and then pause one second:
  for (int i = 0; i < 3; i++)
  {
    digitalWrite(Player1RelayPin, HIGH);  // Turn on Player 1 lights
    digitalWrite(Player2RelayPin, HIGH);  // Turn on Player 2 lights
    delay(300);
    digitalWrite(Player1RelayPin, LOW);  // Turn off Player 1 lights
    digitalWrite(Player2RelayPin, LOW);  // Turn off Player 2 lights
    delay(300);
  }
  delay(700);  // Add this delay to the 300 milliseconds above to get 1 second

  // Turns start with Player 1
  TurnPlayer1 = true;  // Player 1's turn
  digitalWrite(Player1RelayPin, HIGH);  // Turn on Player 1 lights
  digitalWrite(Player2RelayPin, LOW);  // Turn off Player 2 lights
  PlayerTurnStartTime = millis();
}