There are a number of BKR Achievements that require active chart positions. Which means that you can qualify today, but not tomorrow. Does that mean people can lose achievements? Or does it mean having had the required active chart positions at one point in the past?
(hide) If you want to play a game with an opponent of a similar level, you can define a required BKR range for a new game invitation. Then nobody with a BKR outside this range will be able to see/accept it. (Katechka) (show all tips)