Lutris is the impressive all-in-one solution for managing games on Linux, bundling tons of sources of Linux releases from different stores under one roof as well as emulators, compatibility layers and more.
Just recently on October 19 they put up the Beta of the new 0.5.8 release, and it includes some pretty huge changes and improvements all across the application. The way it actually works under the hood has been completely changed in many ways, along with the way you add games to it.
Instead of manually importing games, it now attempts to sync up with your library across other stores like GOG, Humble and Steam. Adding games from the Lutris website using their scripts to set things up is also now in its own section, just called Lutris and it no longer depends on having install scripts for 3rd party services as Lutris will now run stuff with an "auto-generated" script but scripts on the Lutris database will take precedence if available.
Actual installers have changed too and they now give a choice between downloading the files needed, or custom provided files and game banners and icons are now downloaded directly from the services linked. When installing from GOG for example, it will now attempt to pick up bonus content like soundtracks and manuals and offer to download them too when you pick a game. For people writing runners, the scripts that used to support all the different way to run games, you can now write them in JSON instead of Python, which opens it open to even more people although that way only covers simple methods but some of their runners have already moved over to JSON like dgen, ppsspp, citra, ags, virtualjaguar.
Lots of UI changes to make it cleaner, like the big sidebar moving to a smaller sleeker section at the bottom as shown above with the platform details and play button. There's also now a Favourites section, so you can set a few of your favourites to have them in a dedicated area.
Since this is a Beta, keep in mind there will be bugs but what they're doing with it really does sound good. Once the issues are ironed out, and Lutris 0.5.8 is released in full it should be a big improvement.