SVN allows you to access the latest source code

GCompris code is available from the GNOME Subversion repository.

From the Gnome web site:

Many people who are interested in working with GNOME development find their first hurdle is figuring out how to use Subversion. This document will be a quick tutorial.

Subversion is a powerful method of allowing many developers work on the same source code. This is possible because each developer checks out a copy of the current version of the source code. Then they each independently work on their personal copy of the sources. When they have made changes, they commit them back to the Subversion repository. The Subversion server takes care of things like trying to merge their changes with those of others. When that doesn’t work, the developer is notified and they do a hand merge of the conflicts.

To get the newest GCompris source from Subversion, you need to have it installed.

The first command you need is:

To read more on Subversion on Gnome go there.

Alternatively you can browse the GCompris code online.