Steam Achievements
Steam Achievements should be working now. Give it a try.
If you were playing, don't worry, when you get to the world map, if you have completed the requirement, it will unlock.
There are some with specific requirements that involve a specific action, if you have already done it, you will need to do it again.
Sorry for any inconvenience. ːsteamfacepalmː
That's all for now! ːsteamhappyː