chess.com Achievements
Lately, I have been focusing my attention on chess.com "Achievements". Currently, I have attained 129/144 of them. Some are unattainable without a premium membership (not to worry, chess.com, I shall return as a premium member eventually).
On the whole, these are a nice gimmick. Many are relatively meaningless, but at least they are engaging. A great marketing "achievement" for chess.com, which surely must have helped the bottom line.
In my assessment, the most difficult "Achievements" are "Chatterbox" and "Legend League". In terms of time required, I would guess "Chatterbox" is a much larger commitment (subjectively speaking), but I suppose we shall see.
I predict I will enter the Legend League within the next five (5) years (I am not actively pursuing it at the moment). I am not so sure about being deemed a "Chatterbox". Regardless, I remain thankful to be engaged with chess in small ways.