minha criação do creeper. quase identico!
<canvas width="600" height="400"></canvas>
<script>
var tela = document.querySelector('canvas');
var pincel = tela.getContext('2d');
pincel.fillStyle = 'darkgreen';
pincel.fillRect(0,0, 350, 300);
pincel.strokeStyle = 'black';
pincel.strokeRect(0,0, 350, 300);
pincel.fillStyle = 'black';
pincel.fillRect(50,60, 90, 90);
pincel.fillRect(210,60, 90, 90);
pincel.fillRect(140,150, 70, 110);
pincel.fillRect(100,190, 40, 110);
pincel.fillRect(210,190, 40, 110);
</script>