This is a demo Express server which downloads releases from GitHub and packages them as 'asar' files ready for atom-shell to run
The client demo is here
https://github.com/shrewdlogarithm/atom-shell-auto-update-demo
Note: this isn't meant to be a working project, just an idea of how you can do this. Feel free to ask questions/raise issues or even make suggestions on how to improve it!