Zoidberg: You make a tag: "Completed".

Barmem: its not the same as marks

Zoidberg: What's a "mark"? Never heard of those.

zeragrin: Maybe he's thinking of like a Green Checkmark or a green dot that can be put onto a game in the library to visually "mark" it as done. If that's what he's thinking it's not a half bad idea. I really enjoy how you can give all the games in your 2.0 library a star rating regardless of what platform they're on. I've started using that, and on Steam when I finish a game I review it to mark it as "completed".

kzadur: Nah, we need a backlog-tag, because that's what we all have. We wouldn't need something like Galaxy 2.0, if we would complete all of our games before buying new ones. ;)

Feed the Bak'laag!

But seriously ... having it officially shown to other players would be a nice feature. Maybe even use it as seen at backloggery.com - mark it yourself and show it as "marked - completed" etc.. Anyway, finished or not is a personal choice in any case. Even games which does track completion rates, doesn't mean you've seen everything, just because it shows you 100%. And achievements mostly doesn't mean it either.

EDIT: some typos and one clarification - missed to write a word

Zoidberg: I literally have a "Backlog" list. :P

zeragrin: Same, it's labeled as "Library" ;p