Minha versão do creeper:
<canvas width="600" height="400"></canvas>
<script>
var tela = document.querySelector('canvas');
var pincel = tela.getContext('2d');
pincel.fillStyle = 'green';
pincel.fillRect(0, 0, 350, 300);
pincel.fillStyle = 'black';
pincel.fillRect(60, 70, 90, 90);
pincel.fillStyle = 'black';
pincel.fillRect(210, 70, 90, 90);
pincel.fillStyle = 'black';
pincel.fillRect(144, 157, 70, 100);
pincel.fillStyle = 'black';
pincel.fillRect(104, 189, 40, 110);
pincel.fillStyle = 'black';
pincel.fillRect(214, 189, 40, 110);
</script>