Not a direct fork but VS Code was built on the foundation of Atom, and heavily inspired by it. People generally consider VS Code to be the successor of Atom, especially after Microsoft bought out the creator of Atom/Electron (Github) and shut down the project.
VS Code is built on the foundation of Monaco. And when you run it in a browser it has nothing common with Atom. And on desktop the only thing from Atom is the runtime Atom shell now called Electron and it is essentially Chrome with some glue for integrating with OS.
Microsoft built several key tools on top of Electron (VSCode being the relevant one here) and became very interested in maintaining control of it... and so bought GitHub when it was up for sale.
> Atom has not had significant feature development for the past several years, though we’ve conducted maintenance and security updates during this period to ensure we’re being good stewards of the project and product. As new cloud-based tools have emerged and evolved over the years, Atom community involvement has declined significantly. As a result, we’ve decided to sunset Atom so we can focus on enhancing the developer experience in the cloud with GitHub Codespaces.
> This is a tough goodbye. It’s worth reflecting that Atom has served as the foundation for the Electron framework, which paved the way for the creation of thousands of apps, including Microsoft Visual Studio Code, Slack, and our very own GitHub Desktop. However, reliability, security, and performance are core to GitHub, and in order to best serve the developer community, we are archiving Atom to prioritize technologies that enable the future of software development.
