Canonical developed Unity as a graphical shell for GNOME and used it as the default desktop environment for Ubuntu. Canonical has since stopped the development of Unity though UBports now maintains it.
Ubuntu Unity Remix is an Ubuntu variant with Unity as the default desktop environment. You can still install Unity if you're running the standard Ubuntu distribution or any other Ubuntu variance. This is because Unity Desktop packages are available in apt's default repository that you can install at the terminal.
$ sudo apt update Hit:1 http://ports.ubuntu.com/ubuntu-ports jammy-security InRelease Hit:2 http://ports.ubuntu.com/ubuntu-ports jammy-proposed InRelease Hit:3 http://us.ports.ubuntu.com/ubuntu-ports jammy InRelease Hit:4 http://us.ports.ubuntu.com/ubuntu-ports jammy-updates InRelease Hit:5 http://us.ports.ubuntu.com/ubuntu-ports jammy-backports InRelease Reading package lists... Done Building dependency tree... Done Reading state information... Done All packages are up to date.
$ sudo apt dist-upgrade --assume-yes Reading package lists... Done Building dependency tree... Done Reading state information... Done Calculating upgrade... Done 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
$ sudo apt install --assume-yes ubuntu-unity-desktop Reading package lists... Done Building dependency tree... Done Reading state information... Done The following additional packages will be installed: a11y-profile-manager-indicator accountsservice-ubuntu-schemas activity-log-manager adium-theme-ubuntu bamfdaemon catdoc cinnamon-desktop-data cinnamon-l10n compiz compiz-core compiz-gnome ##### snipped 0 upgraded, 417 newly installed, 0 to remove and 0 not upgraded. Need to get 244 MB of archives. After this operation, 681 MB of additional disk space will be used. ##### snipped
Use [TAB] key to navigate to the Ok button and press [ENTER] to start configuring LightDM if you're first presented with the following screen. You'll get this screen if you're using a low resolution monitor and/or not running terminal in full screen.
$ sudo reboot
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