Segue a resolução do desafio do creeper.
<canvas width="600" height="400"></canvas>
<script>
var tela = document.querySelector('canvas');
var pincel = tela.getContext('2d');
pincel.fillStyle = 'white';
pincel.fillRect(0,0,600,400);
pincel.fillStyle = 'darkgreen';
pincel.fillRect(00,00,350,300);
pincel.fillStyle = 'black';
pincel.fillRect(215,50,90,90);
pincel.fillStyle = 'black';
pincel.fillRect(55,50,90,90);
pincel.fillStyle = 'black';
pincel.fillRect(145,140,70,100);
pincel.fillStyle = 'black';
pincel.fillRect(215,190,40,110);
pincel.fillStyle = 'black';
pincel.fillRect(105,190,40,110);
</script>