I have VLC media player installed on my laptop. When I download games from IFDB, some formats are stored as (unplayable) media files (VLC-icon and all.)
I’ve worked around this for some time by un- and re-installing VLC, which isn’t that much of a chore, but I wonder if I can fix it once and for all.
It sounds to me as if VLC is registering a file extension that is used for both VLC and the interactive fiction format.
In Windows (I’m guessing this is Windows) you can change what applications are registered for each file type. In windows 10 just click the Windows Logo (formerly known as the start button) and type “file type”. The first or nearly first option should be to choose default applications for a file type. In there you can change a file type to open with a particular application.
You can also right-click a problem file and choose Open with > Choose another app if looking through/filtering the whole list of file types is overwhelming.