More than likely this has been already answered several times. But my searching abilities are not top-notch, hence posting this question:

Where could I find all the artwork of the GOG.com?

I am primarily looking for the discount-sale-times / event artwork, like the variations of the Summer Sale 2016 we had (an example image fro this website).
But all the other artworks of the website (especially form the past) would be grand too.

There's a mad fella that attempts to gather most (or all) of said GOG images here. For the sale artwork, you are looking at the adhoc folder.
I do not keep the news images though, and I haven't updated the unofficial covers or the library images in quite a while.

Thank you for the links; I wish I could choose both replies as the solutions. :D