FATAL ERROR at the start of launch

[Romulator]

Looks like a bad installation or re-installation. The things you have mentioned that are missing should be in the /core/ folder in the redist directory.

Where did you get your retail copy from? Did you install your original retail edition, and then update using the Software Updates page?

Try uninstalling your copy of Amnesia, and then delete any excess files which are leftover, if any, in the redist folder. By default, that is C:/Program Files (x86)/Amnesia - The Dark Descent/redist/ then install your retail copy, then update using the Software Updates link above.