We offer the following options:
GOG Galaxy - our optional client which offers easy installation of games, automatic updates, as well as downloading standalone installers with full protection against download corruption.
GOG Downloader - our old standalone download manager, which offers full protection against download corruption.
Browser downloads - the oldschool option, which lets you just download standalone installers onto your computer, and install them anywhere, at any time. Keep in mind that this method offers no protection against download corruption.
If you would like to learn more about these download options and how to use them, you can find a more detailed explanation and instructions in this support article.