Regolith Linux isn8217t your typical Linux distribution. It falls somewhere in between being a distribution and a desktop environment as it is built on top of Ubuntu. And unlike most typical Linux distributions Regolith doesn8217t have to be installed as a standalone operating system. If you are already using Ubuntu as your operating system then you can install Regolith on top of it for a preconfigured i3 experience.
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Regolith provides you with the ability to quickly and easily set up the i3 window manager while still allowing you to take advantage of all the benefits that Ubuntu and GNOME have to offer.
If you were to install i3 manually then you would have to configure everything yourself. This can take quite some time depending on what you wish to achieve with it. Even then this still doesn8217t guarantee that you will be able to get GNOME apps and tools working alongside i3.