After trying to load a custom game, Amnesia won't launch

[Romulator]

Well, if the main game fails to load, then at some point in time, you have modified the files required to run Amnesia, likely because you did not install a custom story or full conversion correctly.

A simple attempt at fixing would be to reinstall the game in the same directory (it will overwrite incorrect files). If you are using retail, you can download an update suitable for your system from the suitable page in the Technical Support section. If using Steam, perform an integrity check.

Then, re-follow the instructions as stated (hopefully) by the modification. If you are still unable to get it installed, then as Traggey stated, try contacting the developer.