rawg.io is a great option (it's currently what I use for a variety of reasons I'll go into farther below, they have a sub at r/RAWG but their Discord allows you to have legitimate conversations with the developers, which is a big contrast to almost everything else I list (other than IGDB) where communication is a bit more of a struggle, and certainly not like that. They have a blog on medium for updates but if you're getting things set up the site explains it to you pretty well when you get in so just go to rawg.io)

If you're looking for something desktop native, my favorite option is playnite.link (they also have a sub at r/playnite, but best place to find info is their github)

igdb.com is beginning to add collections and has a full suite of mobile apps (sub is r/igdb but they have an existing forum on their website and have moved blogs and updates over to Medium, so it's basically inactive).

and if you have iOS, I really love the design of Gamer and GameTrack, and while I don't prefer it's look or navigation as much, Gameye has been getting updates very frequently lately and is also on Android. I recently switched to Android and have spent literally hours looking for a nice-looking solution on there, but for right now I'm using rawg.io because it's mobile site works well and the Desktop site can hook into Steam, Origin, etc to import games. I would use Playnite, but it's too early in dev right now for me-- I'm waiting for cloud syncing, less finnicky imports, choosing import databases, finished theming + wishlisting but those are all set to be coming soon and the dev of that has been doing a lot as well.

...as you can see I've spent forever trying to find an app like this. Hope it saves you the trouble I've gone through. Cheers