Arduino memory game - arduino

Question

This game has 4 leds and 4 buttons. the game is turning RANDOMLY those leds ON and OFF.
The player should be able to push the right button whenever he sees one led to be turned ON.
The leds should be turning ON and OFF with incerasing speed, so reaction time of a player is shorter and shorter
I have this code but i just know how to add more leds and buttons.
const int BUTTON1 = A0;
const int BUTTON2 = A1;
const int BUTTON3 = A2;
const int BUTTON4 = A3;
int LED1 = 2;
int LED2 = 3;
int LED3 = 4;
int LED4 = 5;
int ran;
int right = 0;
int ledOrder[9];
int guessOrder[9];
void setup()
{
Serial.begin(9600);
pinMode(LED1,OUTPUT);
pinMode(LED2,OUTPUT);
pinMode(LED3,OUTPUT);
pinMode(LED4,OUTPUT);
pinMode(BUTTON1,INPUT);
pinMode(BUTTON2,INPUT);
pinMode(BUTTON3,INPUT);
pinMode(BUTTON4,INPUT);
}
void randomLed() {
for (int i = 0; i < 9; i++) {
ran = random(1,20);
if (ran < 11) {
digitalWrite(LED1,HIGH);
delay(500);
digitalWrite(LED1,LOW);
ledOrder[i] = 1;
}
else {
digitalWrite(LED2,HIGH);
delay(500);
digitalWrite(LED2,LOW);
ledOrder[i] = 2;
}
delay(500);
}
}
void btnClick() {
int ans = 0;
while (ans < 9) {
if (digitalRead(BUTTON1) == HIGH) {
guessOrder[ans] = 1;
ans++;
while (digitalRead(BUTTON1) == HIGH) {
}
}
else if (digitalRead(BUTTON2) == HIGH) {
guessOrder[ans] = 2;
ans++;
while (digitalRead(BUTTON2) == HIGH) {
}
}
}
}
void loop() {
Serial.print("Press button1 to start \n");
while (digitalRead(BUTTON1) == LOW) {
}
randomLed();
btnClick();
for (int i = 0; i < 9; i = i + 1) {
Serial.print("Guess: ");
Serial.print(guessOrder[i]);
Serial.print(" Answer: ");
Serial.print(ledOrder[i]);
if (guessOrder[i] == ledOrder[i]) {
Serial.print(" Right");
right++;
} else {
Serial.print(" Wrong");
}
Serial.print("\n ");
}
Serial.print(right);
Serial.print("/9\n");
delay(2000);
}

Answer 1

If I understand your question correctly, you would like to increase the led blink rate(when the LED's come on) each time the user gets the previous game right. If this is true you should try to put loop in for/if the user got the the previous one(game) right it will increase blink rate by a simple increment( I++;). Comment if you feel this is clarified enough or if your asking for something else