Monstruo Creeper

Asi me quedo, sugerencias de mejora, o que hice mal

<meta charset="UTF-8">

<h1>MONSTRUO CREEPER </h1>


<canvas  width="600" height="400"></canvas>

<script>
    var pantalla = document.querySelector("canvas");
    var pincel = pantalla.getContext("2d")


    pincel.fillStyle = "lightgrey"
    pincel.fillRect(0,0,600,400);

    pincel.fillStyle = "green"
    pincel.fillRect(120,40,350,300);

    pincel.fillStyle = "black"
    pincel.fillRect(172,80,90,90);

    pincel.fillStyle = "black"
    pincel.fillRect(328,80,90,90);

    pincel.fillStyle = "black"
    pincel.fillRect(260,170,70,100);

    pincel.fillStyle = "black"
    pincel.fillRect(220,220,40,110);

    pincel.fillStyle = "black"
    pincel.fillRect(328,220,40,110);


</script>

<h1>Elaborado por: Richard Tomalá :) </h1>