function play(){
  //move bird #1 (enemy)
  if(bird.x<20){
    bird.velocityX=4;
    bird.setAnimation("bird_right");
  } else if(bird.x>380){
    bird.velocityX=-4;
    bird.setAnimation("bird_left");
  } 
  //move bird #2 (enemy)
  if(bird2.x<20){
    bird2.velocityX=4;
    bird2.setAnimation("bird_right");
  } else if(bird2.x>380){
    bird2.velocityX=-4;
    bird2.setAnimation("bird_left");
  }
  //move butterfly (you)
  if(keyDown("up")&&butterfly.y>20){
    butterfly.y-=5;
  }else if(keyDown("down")&&butterfly.y<380){
    butterfly.y+=5;
  }
  //win or loss
  if(butterfly.collide(bird)){
    lose();
  }else if(butterfly.collide(bird2)){
    lose();
  }else if(butterfly.y<=25){
    win();
  }
}

//-------------------------------------------------------

function draw() {
  drawSprites();
  //playing the correct mode
  if (mode=="1 - opening") {
    opening();
  } else if (mode=="2 - start") {
    start();
  } else if (mode=="3 - play") {
    play();
  } else if (mode=="4 - win") {
    win();
  } else if (mode=="5 - lose") {
    lose();
  }
  
  //space to move on
  if (keyWentDown("space")) {
    if (mode=="1 - opening") {
      mode = "2 - start";
    } else if (mode=="4 - win") {
      mode = "2 - start";
    } else if (mode=="5 - lose") {
      mode = "2 - start";
    }
  }
}