Screen goes completly dark if I'm not looking directly into a source of lightning

[plutomaniac]

Uninstall the game via steam (right click it > remove local content) and let it redownload. After the game is installed, before you run it, it might also help to let the game recreate the settings and profiles. That can be done by renaming the folder Amnesia at Documents to Amnesia_OLD(don't delete it because your saves are in there! If the game is fixed we will move them afterwards. Unless you don't have any saves, in that case delete it).