I was about to also mention Gource.

Here's a render I made in December, "1500 Commits (39 months) in 1 and a half minutes": https://www.youtube.com/watch?v=szhYhph4C2U

And he's another one I made a few years ago, "100 Commits (18 months) in 1 minute": https://www.youtube.com/watch?v=aIN4mOdL0d0

I used Gource to visualize a hackathon, we had everyone start from a templated repo so it was really easy to show the entirety of participants coding activity (albeit at a macro level)