In the era of dial-up and early broadband, physical game discs ruled retail. However, FTP servers thrived for three main reasons:
Why run your own FTP server? Maybe you want to share a library of DRM-free games with friends on a LAN, or back up your GOG installers. pc games download ftp server
Many game developers, especially in the indie and open-source spaces, still use FTP for distribution. Examples include: In the era of dial-up and early broadband,