To install it, extract the contents of the .ZIP file to your main_menumain folder. For Steam users, this is located at "C:Program FilesSteamSteamappsCommonAmnesia the dark descentmain_menumain". For non-Steam users, this is located at "C:Program FilesAmnesia - the dark descentRedistmain_menumain". These instructions are for a Windows OS, I have no experience with other systems, so the folder address may vary. Thanks for installing!