So I left this alone for a while, until this week. I decided I'd have a look and see what it's all about. And it's actually quite fun. Of course, so far, I've only earned the most common achievements but by just looking at the locked achievements, I see some new ways to do existing things, and I see some stuff I didn't even know about. Pretty cool eh?
Installing git-achievements is just a matter of following the steps in the README. I forked the repository, cloned it to my local machine, and editted my .profile file to include my git-achievements clone into my PATH, and then alias the git-achievements executable to the git command. I have also set the achievement.upload setting, so that I now share my achievements. It's fun, simple and doesn't really interfere much with your normal day to day Git usage.