Create Retro Snake Game with Arduino Nano and SSD130 OLED

#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define SNAKE_BLOCK 2 // Size of each snake block
#define MAX_SNAKE_LENGTH 50

#define OLED_RESET -1 // Reset pin # (or -1 if sharing Arduino reset pin)
#define OLED_ADDRESS 0x3C     // I2C address of the display
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

int snakeX = 32, snakeY = 32;
int dirX = 0, dirY = -SNAKE_BLOCK;

int foodX, foodY;

const int buttonUp = 2, buttonDown = 3, buttonLeft = 4, buttonRight = 5;

int snakeBody[MAX_SNAKE_LENGTH][2];
int snakeLength = 1;
int gameSpeed = 200;

void setup() {
  Serial.begin(9600);
  if(!display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDRESS)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  display.clearDisplay();

  pinMode(buttonUp, INPUT_PULLUP);
  pinMode(buttonDown, INPUT_PULLUP);
  pinMode(buttonLeft, INPUT_PULLUP);
  pinMode(buttonRight, INPUT_PULLUP);

  snakeBody[0][0] = snakeX;
  snakeBody[0][1] = snakeY;

  placeFood();
}

void loop() {
  readInput();

  moveSnake();

  if (snakeX == foodX && snakeY == foodY) {
    increaseSnake();
    placeFood();
    gameSpeed = max(50, gameSpeed - 10);
  }

  if (checkCollision()) {
    displayGameOver();
    return; // End the current loop cycle to avoid extra drawing and updating
  }

  drawScreen();

  delay(gameSpeed);
}

void readInput() {
  if (digitalRead(buttonUp) == LOW && dirY != SNAKE_BLOCK) {
    dirX = 0; dirY = -SNAKE_BLOCK;
  }
  if (digitalRead(buttonDown) == LOW && dirY != -SNAKE_BLOCK) {
    dirX = 0; dirY = SNAKE_BLOCK;
  }
  if (digitalRead(buttonLeft) == LOW && dirX != SNAKE_BLOCK) {
    dirX = -SNAKE_BLOCK; dirY = 0;
  }
  if (digitalRead(buttonRight) == LOW && dirX != -SNAKE_BLOCK) {
    dirX = SNAKE_BLOCK; dirY = 0;
  }
}

void moveSnake() {
  int prevX = snakeX, prevY = snakeY;
  snakeX += dirX;
  snakeY += dirY;

  for (int i = snakeLength - 1; i > 0; i--) {
    snakeBody[i][0] = snakeBody[i - 1][0];
    snakeBody[i][1] = snakeBody[i - 1][1];
  }

  snakeBody[0][0] = snakeX;
  snakeBody[0][1] = snakeY;
}

void increaseSnake() {
  if (snakeLength < MAX_SNAKE_LENGTH) {
    snakeLength++;
  }
}

bool checkCollision() {
  if (snakeX < 0 || snakeX >= SCREEN_WIDTH || snakeY < 0 || snakeY >= SCREEN_HEIGHT) {
    return true;
  }

  for (int i = 1; i < snakeLength; i++) {
    if (snakeX == snakeBody[i][0] && snakeY == snakeBody[i][1]) {
      return true;
    }
  }

  return false;
}

void placeFood() {
  do {
    foodX = (random(0, SCREEN_WIDTH / SNAKE_BLOCK) * SNAKE_BLOCK);
    foodY = (random(0, SCREEN_HEIGHT / SNAKE_BLOCK) * SNAKE_BLOCK);
  } while (checkFoodCollision());
}

bool checkFoodCollision() {
  for (int i = 0; i < snakeLength; i++) {
    if (foodX == snakeBody[i][0] && foodY == snakeBody[i][1]) {
      return true;
    }
  }
  return false;
}

void drawScreen() {
  display.clearDisplay();

  for (int i = 0; i < snakeLength; i++) {
    display.fillRect(snakeBody[i][0], snakeBody[i][1], SNAKE_BLOCK, SNAKE_BLOCK, SSD1306_WHITE);
  }

  display.fillRect(foodX, foodY, SNAKE_BLOCK, SNAKE_BLOCK, SSD1306_WHITE);

  display.display();
}

void displayGameOver() {
  display.clearDisplay();
  display.setTextSize(2);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(0, 0);
  display.println("Game Over");
  display.display();
  delay(2000);

  snakeLength = 1;
  snakeX = 32;
  snakeY = 32;
  dirX = 0;
  dirY = -SNAKE_BLOCK;
  gameSpeed = 200;

  snakeBody[0][0] = snakeX;
  snakeBody[0][1] = snakeY;

  placeFood();
}