arduboy code

//DinoSmasher

#include <Arduboy2.h>
Arduboy2 arduboy;
#define GAME_TITLE 0
#define GAME_PLAY 1
#define GAME_OVER 2
#define GAME_HIGH 3

int gamestate = GAME_TITLE;

#define WORLD_WIDTH    20
#define WORLD_HEIGHT  4
int world[WORLD_HEIGHT][WORLD_WIDTH] = {
  { 0, 0, 0, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0 },
  { 0, 1, 1, 1, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1 },
  { 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0 },
  { 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0 }
};

void drawworld() {
  for (int y = 0; y < WORLD_HEIGHT; y++) {
    for (int x = 0; x < WORLD_WIDTH; x++) {
      arduboy.print(world[y][x]);
    }
    arduboy.print("\n");
  }
}

void titlescreen() {
  arduboy.setCursor(0, 0);
  arduboy.print("Title Screen\n");
  if (arduboy.justPressed(A_BUTTON)) {
    gamestate = GAME_PLAY;
}
}
void gameplay() {
  arduboy.setCursor(0, 0);
  arduboy.print("Gameplay\n");
  drawworld();
  if (arduboy.justPressed(A_BUTTON)) {
  gamestate = GAME_OVER;
}
}
void gameoverscreen() {
  arduboy.setCursor(0, 0);
  arduboy.print("Game Over Screen\n");
  if (arduboy.justPressed(A_BUTTON)) {
  gamestate = GAME_HIGH;
}
}
void highscorescreen() {
  arduboy.setCursor(0, 0);
  arduboy.print("High Score Screen\n");
  if (arduboy.justPressed(A_BUTTON)) {
  gamestate = GAME_TITLE;
}
}


void gameloop() {

  switch(gamestate) {

    case GAME_TITLE:
      titlescreen();
      break;

    case GAME_PLAY:
      gameplay();
      break;

    case GAME_OVER:
      gameoverscreen();
      break;

    case GAME_HIGH:
      highscorescreen();
      break;

  }

}

void setup() {

  arduboy.begin();
  arduboy.setFrameRate(45);
  arduboy.display();
  arduboy.initRandomSeed();
  arduboy.clear();

}

void loop() {

  if(!(arduboy.nextFrame())) {
    return;
  }

  arduboy.pollButtons();
  arduboy.clear();
  gameloop();
  arduboy.display();
}