I created a collaborative drawing room for multiple users on the server using websocket. To start the drawing, simply click on the canvas to designate where to start your line. They are limited to draw only straight lines horizontally and vertically, using arrow keys on their keyboard, because I believe limitations provide more creativity into artwork. They can choose brush size between small, medium, and big by clicking buttons.
Here is the demo: http://188.8.131.52:9999/index.html