   if (arduboy.pressed(RIGHT_BUTTON) && (spaceShip.x < MAX_SHIP_X)) {
     spaceShip.x++;
   }
-  
+
   if (arduboy.pressed(LEFT_BUTTON) && (spaceShip.x > MIN_SHIP_X)) {
     spaceShip.x--;
   }
-  
+
   if (arduboy.pressed(UP_BUTTON)) {
     if (spaceShip.y > MIN_SHIP_X) {
       spaceShip.y--;

// Main program loop
void loop() {
  byte result;
  
  // TODO alternate between titleScreen and highScoreScreen on a timer
  // until user pressed a button
  result = titleScreen();

  switch(result) {
    case TITLE_CREDITS:
      creditsScreen();
      break;

    if (arduboy.everyXFrames(9)) {
      spaceShip.frame++;
    }
    if (spaceShip.frame  > 4) {
      spaceShip.frame = 4;
    }
  }

  if (arduboy.pressed(A_BUTTON)) {
    bullets[0].set(spaceShip.x, spaceShip.y + (spaceShip.height / 2) - 1);
  }

  if (arduboy.notPressed(UP_BUTTON) && arduboy.notPressed(DOWN_BUTTON)) {
    if (arduboy.everyXFrames(12)) {
      if (spaceShip.frame > 2) {
