Cyber Grand Challenge has released the CGC DECREE Operating System and examples via two mediums: github, and a binary repository.
All of the released CGC source code exists on Github at https://github.com/CyberGrandChallenge.
The individual CGC repositories can be found on the above page and checked out via:
git clone https://github.com/CyberGrandChallenge/binutils Cloning into 'binutils'... remote: Counting objects: 7, done. remote: Compressing objects: 100% (5/5), done. remote: Total 7 (delta 0), reused 7 (delta 0) Unpacking objects: 100% (7/7), done. Checking connectivity... done.
For those new to git, github is a good source of help at https://help.github.com/
The CGC binaries can be found at http://repo.cybergrandchallenge.com. These include a Vagrant Virtual Machine and the debian package files.