I believe you can use a program called wine to run some games in mac that are windows based.....hopefully someone else more knowledgable can help if that answer isn't good enough for your needs. :)

Note: I don't have a mac, but I've used this method on Linux.

You can, but you need to use a program called innoextract to unpack the GOG game installers.
Then, you need a Mac version of DOSBox which you'll have to find and configure yourself for each game.

You can read more info on this thread:
https://www.gog.com/forum/catacombs_pack/extract_files_from_installer_without_installing

http://boxerapp.com/ might be what you want.

Some games are packaged with (a Windows version of) DOSBox to begin with (because they're DOS games and thus don't work on modern versions of Windows as-is), others are Windows games. I can't say at the moment which games are which (especially considering some had both Windows and DOS versions back in the day).

Depending on whether it's a Windows or a DOS games, there are a few different ways to run them on macOS.

Windows game: run the game through PlayOnMac, CrossOver, Wineskin, WineBottler, or even Wine itself depending on your preferences.
DOS game: You may be able to do the same as for Windows games (I don't know, haven't tried), or you can -as some others have said- extract the game and run it through a macOS version of DOSBox (or something intended to make DOSBox easier, such as Boxer).

Thanks everyone for your help and great advice.