This is a really simple, but kind of fun game. I first saw an implementation of it on Android three years ago. I've implemented it here using JavaScript. I intend to have two implementations of the rendering part. One which uses canvas and one which uses a bunch of div elements. Right now the canvas part is working.
You can see it running by going to http://mrexception.com/projects/colours/
Building it requires Rake and a few ruby gems. It also requires the coffeescript compiler, which requires node. Get ruby up and running, and run Bundle. Then run Rake to compile it all into the site/ directory. It's then ready to use from a browser. I also use guard while developing. You can run guard in the root directory and a web server will be started. You can view the game by going to http://localhost:3000