There's already a topic about achievements here, but additionally i would be really grateful to have a manual one too. We could choose between adding achievements manually or as you said, having them automatically detected in the Steam account, Playstation, Xbox etc.

There are sites out there with achievement tracking, but they are not for me as I don't want to connect my account to them and they only accept it by automatically detecting the achievement in the Steam/Playstation/Xbox account etc (like Exophase). Supposing you're going to make a Leaderboard and don't want people cheating because they can freely add achievements, you could simply make them be removed from the rankings if they choose to add achievements manually. I believe this is one of the reasons why in achievement sites you can't add manually, but if that's the case just remove the person from the ranking, simple as that...

Also sorry for the bad english