Openpixels is a project of mine to create a free and open source artistic framework for game projects in any language or platform. It is going pretty well.

You can just download a zip or tar.gz of the latest version.

You may want fork it or get a git working copy of it to later make your own contributions to the project. In this case:

apt-get install git-core
cd ~
git clone git://github.com/silveira/openpixels.git

You will see something like this:

Cloning into openpixels...
remote: Counting objects: 129, done.
remote: Compressing objects: 100% (126/126), done.
remote: Total 129 (delta 17), reused 0 (delta 0)
Receiving objects: 100% (129/129), 784.52 KiB, done.
Resolving deltas: 100% (17/17), done.

And now you have a repository clone at ~/openpixels and you can start hacking.