Here’s an explanation from the originator:

So I thought it would be a cool thread idea to combine GAF’s boxart fetishism with a Photoshop thread (who doesn’t love these?). Partly inspired by AniHawk’s magazine ad thread, I decided to make a thread about “The GAF Collection”, a theoretical series of video game releases for the more serious collectors (à la The Criterion Collection, hence the name). The Criterion Collection is known for its stunning boxarts just as much as it is for its high quality movie transfers. I think it’d be cool to try this with video games, who have boxarts traditionally bombarded with way too many ugly labels, ratings, seals, and logos.