Hello.

I remember the 7th guest took several CD-ROMs (2 or 3) when it was released. Yet, GOG mentions a 528Mb download on the game page. Are there missing stuffin this version ? Or is the video even more compressed than it was at the time ?

Thanks for your help.

Not compressed, just packed. ;)
And AFAIK there were just 2 CDs, with soundtrack on the 2nd disc which could be played in any CD Player, so it's not that much difference in size.

OK.

Thanks a lot for your answer :-)

And even then the second disc was only used in the context of the game to access the Attic level of the house, so it can't have contained much content.

Actually the GOG version is compressed. The RedBook audio has been compressed to OGG. I myself can't really tell the difference, but it would have been nice to have had the tracks in a lossless format such as FLAC.

Actually, he didn't ask about audio compression. :p

I believe the audio compression is relevant to the topic starter's question.
He was wondering why the file size was so small and the audio compression is why. If the audio was uncompressed, it would add about 270mgs more.