Just wanted to notify all that the editor tools for Amnesia: The Dark Descent are out. These are the same tools that we used the create the game, so at a minimum you will able to do all that is done in the game.
All info is being collected here:
I suggest you start by first downloading the tools here, then follow the guide here and finally start checking some tutorials.
If you have any questions about the editors, please use our modding forum found here:
Happy editing! :)
NOTE: Only windows version released so far. Other platforms coming shortly!