Memory

const int ledPin[3] = {3, 4, 5};
const int buttonPin[3] = {6, 7, 8};
const int rgbPin[3] = {9, 10, 11};

int difficulty = 1;
int currLevel[10];
int player[10];
boolean nextLevel = true;

void rgbLed(int red, int green, int blue, unsigned long time=0){
  analogWrite(rgbPin[0], red);
  analogWrite(rgbPin[1], green);
  analogWrite(rgbPin[2], blue);
  if(time>0){
    delay(time);
    for(int i=0; i<3; i++)
      digitalWrite(rgbPin[i], LOW);
  }
}

void level(){
  Serial.print("level(): ");
  for(int i=0; i<difficulty; i++){
    if(nextLevel)
      currLevel[i] = int(random(0, 3));
    Serial.print(currLevel[i]);
    digitalWrite(ledPin[currLevel[i]], HIGH);
    delay(500);
    digitalWrite(ledPin[currLevel[i]], LOW);
    delay(300);
  }
  Serial.println("");
  nextLevel = true;
}

void input(){
  Serial.println("input()");
  for(int i=0; i<difficulty; ){
    for(int j=0; j<3; j++){
      if(digitalRead(buttonPin[j]) == HIGH){
        player[i] = j;
        i++;
        Serial.print("Pressed: ");
        Serial.println(j);
        delay(200);
        break;
      }
    }
  }
}

void setup(){
  randomSeed(analogRead(0));
  Serial.begin(9600);
  for(int i=0; i<3; i++){
    pinMode(ledPin[i], OUTPUT);
    digitalWrite(ledPin[i], LOW);
    pinMode(buttonPin[i], INPUT);
    pinMode(rgbPin[i], OUTPUT);
    digitalWrite(rgbPin[i], LOW);
  }
  // Blink leds
  for(int i=0; i<3; i++){
    digitalWrite(ledPin[i], HIGH);
    delay(300);
    digitalWrite(ledPin[i], LOW);
  }
  // Blink rgb led in green
  rgbLed(0, 255, 0, 1000);
  Serial.println("Ready");
}

void loop(){
  Serial.print("Difficulty: ");
  Serial.println(difficulty);
  level();
  input();
  for(int i=0; i<difficulty; i++){
    if(player[i] != currLevel[i]){
      nextLevel = false;
      rgbLed(255, 0, 0, 500);
      return;
    }
  }
  rgbLed(0, 255, 0, 1000);
  difficulty++;
  if(difficulty > 10){
    rgbLed(0, 255, 0, 1000);
    rgbLed(0, 255, 0, 1000);
  }
  delay(300);
}