user62320: Here's the code up to the error.
const int R = 12;
const int G = 10;
const int Y = 8;

const int PBR = 13;
const int PBG = 11;
const int PBY = 9;
const int pinNum = 3;
const int speaker = 2;

int LED = 0;
int gameStage = 0;

const int winNum = 2;
int gamePoint[winNum];
int rounding = 0;

unsigned long lastTime = 0;
unsigned long pause = 1000;

void ledState(int ledNum);
void clue(int rounding);
void begin_game();
void play();
void winning_sound();
void win();
void lose();
void lose_sound();
boolean inputWait(int buttonNum);


void setup() {
Serial.begin(9600);

pinMode(R, OUTPUT);
pinMode(G, OUTPUT);
pinMode(Y, OUTPUT);
pinMode(PB1, INPUT);
pinMode(PB2, INPUT);
pinMode(PB3, INPUT);
pinMode(speaker, OUTPUT);

randomSeed(analogRead(0));
}

void loop() {

if (gameStage == 0)
{
int PBvalue1 = digitalRead(PB1);
int PBvalue2 = digitalRead(PB2);
int PBvalue3 = digitalRead(PB3);
  if (PBvalue1 && PBvalue2 && PBvalue3 == 0)
  {
    begin_game();
  }
  else
  {
    Serial.println("button Pressed");
    ledState(-1);
    rounding = 0;
    delay(1500);
    gameStage = 1;
  }
}
if (gameStage == 1)
{
  **play();** Error
}

if (gameStage == 2)
{
  delay(750);
  winning_sound();
  **win();
  win();
  win();
  win();** Error
  delay(1500);
  gameStage = 0;
}

if (gameStage = 3)
{
delay(750);
lose_sound();
**lose();
lose();
lose();** Error
delay(1500);
gameStage = 0;
}

}


user61380: Lines 5,6,7 you use PBR, PBG and PBY,
Lines 39,40 and 41 you use PB1, PB2 and PB3 
Again in your void loop() you reference PB1, PB2 and PB3

62320: <p>Here's the code up to the error.</p>

<pre><code>const int R = 12;
const int G = 10;
const int Y = 8;

const int PBR = 13;
const int PBG = 11;
const int PBY = 9;
const int pinNum = 3;
const int speaker = 2;

int LED = 0;
int gameStage = 0;

const int winNum = 2;
int gamePoint[winNum];
int rounding = 0;

unsigned long lastTime = 0;
unsigned long pause = 1000;

void ledState(int ledNum);
void clue(int rounding);
void begin_game();
void play();
void winning_sound();
void win();
void lose();
void lose_sound();
boolean inputWait(int buttonNum);


void setup() {
Serial.begin(9600);

pinMode(R, OUTPUT);
pinMode(G, OUTPUT);
pinMode(Y, OUTPUT);
pinMode(PB1, INPUT);
pinMode(PB2, INPUT);
pinMode(PB3, INPUT);
pinMode(speaker, OUTPUT);

randomSeed(analogRead(0));
}

void loop() {

if (gameStage == 0)
{
int PBvalue1 = digitalRead(PB1);
int PBvalue2 = digitalRead(PB2);
int PBvalue3 = digitalRead(PB3);
  if (PBvalue1 &amp;&amp; PBvalue2 &amp;&amp; PBvalue3 == 0)
  {
    begin_game();
  }
  else
  {
    Serial.println("button Pressed");
    ledState(-1);
    rounding = 0;
    delay(1500);
    gameStage = 1;
  }
}
if (gameStage == 1)
{
  **play();** Error
}

if (gameStage == 2)
{
  delay(750);
  winning_sound();
  **win();
  win();
  win();
  win();** Error
  delay(1500);
  gameStage = 0;
}

if (gameStage = 3)
{
delay(750);
lose_sound();
**lose();
lose();
lose();** Error
delay(1500);
gameStage = 0;
}

}
</code></pre>
 61380: <p>Lines 5,6,7 you use PBR, PBG and PBY,</p>

<p>Lines 39,40 and 41 you use PB1, PB2 and PB3 
Again in your void loop() you reference PB1, PB2 and PB3</p>
