To put the Pen Up/Down, press the Space key. To change the color, press keys 1 to 9, 1 being Purple and 9 being Red. For more precise coloring, use the Up and Down arrow keys. To move the Pen, use W,S,A,D, or click and hold the Z key. To reset, click the X key. To change the Pen size, use the Left arrow key to shrink and the Right arrow key to enlarge. Use the B key to change the background.
Not the most original thing I've made, but I have been playing around with some of the more complex parts of Scratch.