"Beaten" games without achievements do not count as "Completed".
As above. Is this intentional?
Hey, "Completed" is a special category on the google charts used for games where all achievements have been unlocked.
It's not a true category as it can't be used to filter ( "completed" games are still tracked as "unplayed"/"played"/"beaten"/"blacklisted" for filtering & internal purposes ).
But you are right, currently it's not possible to have a game in the "complete" category that does not have achievement support. Though I'm not quite sure how to change that. It is intentional, for now. In the end it'd be nice if players themselves could mark a non-achievement game as "completed" in addition to marking it as beat, but it will probably take some time to implement such a feature ( the main problem is that there isn't much room for extra buttons ).