Gyre, Zeronus, (and in the context of the Killzone universe-), Mars and the Moon are all mentioned-only locations.
Vekta and Helghan are the only locations listed in the article which the player actually visits in the games. Due to the presence of both mentioned-only locations and visited locations, it would be wise to add the article to both categories.
If we only have to pick one, I would choose mentioned-only, seeing as there are more mentioned-only human colonies in the article than there are visited ones.
Though as it would be unwise to pick only one category when this article can be in both categories, as it has content from both categories, I will be re-adding the article to the category.
Whoopsie daisies, sorry about the sig.