Continue (Y, n): Y
Previous version detected, trying to uninstall…
Installing MonoGame SDK…
Installing MonoDevelop Addin…
Creating launcher items…
gtk-update-icon-cache: Cache file created successfully.
Adding mimetype…
To uninstall MonoGame SDK you can run “monogame-uninstall” from terminal.
destructor@babylon-5:~/Завантаження > monogame-
monogame-pipeline-tool monogame-uninstall
MonoGame is not installed in the GAC (which is that list of assemblies you posted a screenshot of). You can add a reference by browsing to the installation folder and selecting the right dll.
Alternatively you can use NuGet. If you install MD 6 MonoGame will install project templates to create a new game which is easier.