+Rep Also helped me with that Hitman achievment.

Thanks for helping me with that Hitman achievement

Hey! Thanks for your feedback and kind words!
As for achievements - as soon as you unlocked one achievement in a game it will affect AGC - the only exception is if the developer removes all achievements and does not add any back. If the dev adds other achievements it will count as 0%.
If a game has only playtime on it but no achievements unlocked it will not count in any case - even if the developer adds achievements later. That's why we distinguish between just "played" and "started".
As for Crusader Kings II - I'm not to familiar with that game but the above applies to this game as well.
Hope this answered your questions?

12 Perfect games e 61% Completion rate =o

<3