Ok, some suggestions. Don’t know if some actually already exist.
-Make a “play later” list (like the “watch later” on YouTube)
-Give users the possibility to create and share playlists of games
-Make the search box bigger, and more useful
-Put a link to all the games recently uploaded on the homepage (or is it me and i can’t find it?)
-Simplify the design of the site. Less is more.
-Give the possibility to organize tournaments or direct challenges also with non-mulyplayer games. You could challenge a friend, or a group of users, and see who achieves the highest score.
Hope this helped. Peace.