Just found this thread while searching how to do exactly this. I bought the GDC bundle to help out people, but I intend to play maybe 2-3 games out of the 100+ plus that are now crowding my library. I'd love to just tag the ones I want into a collection and mass dump the rest into a bucket that pretends they don't exist unless I specifically look in there. Currently when I go into my library page all the stuff I don't want to see is listed at the very top of the page under Things I Own. I don't have a whole lot of games here, so I haven't needed collections to keep things organized. Literally everything I had was easily visible where I wanted to see it. Now it's not.