Code swarms are a fascinating way to visualize the thousands of interactions between a project’s developers and its files. Developers and files are represented as moving elements. So when a developer makes changes to a file, it will briefly light up and fly towards that developer. The code swarm will only show files that have been changed recently and developers who’ve made a recent change. Conversely, when a file or developer has not been active for a while, they will fade away.

Visualization: FreshBooks.com code-base over time
freshbooks.com