Most of the DLCs of this game are hundreds of MBs in size, but there are two that are only 6MB - From the Ashes and Treasures of the Past.

I bought and installed From the Ashes and, unless I'm missing something, these are the only files that it added (in addition, to updating the EULA.txt file):

goggame-1201995925.hashdb
goggame-1201995925.ico
goggame-1201995925.info
unins002.dat
unins002.exe
unins002.ini
unins002.msg

Obviously none of these are actual game files, and I understand that this is a DLC which data is already included in the base game files and the only thing I paid for is unlocking it, but how does the DLC technically unlock? Does the game check for one of the above files or something?
Everything works fine BTW, and I know it's probably not unique to this game, but it's the first time I noticed this and I'm just curious :)