We have fixed a bug regarding the the problem to unlock achievements.
Achievements which should have been unlocked already, were not reflected on Steam.
After updating to version 1.1.3, simply starting the game will make everything in sync.
Players who have already unlocked the achievements should see the pop-up at the top-left corner on the main screen.
(The pop up will just be a generic one, if no achievements had been unlocked prior to the update.)
We would also like to take this opportunity to thank our amazing player @KnightAvenger who reported this bug (^^)