It seems to be a 3-day thing from the information on the modlog, but I would first try to talk to the moderators before trying to post on the same community again, maybe clarifying that you are the original author, and you plan to maintain/update them, or that maybe the title should not include [old guide] or something like that, and that the purpose of these post is to share information, get feedback and generate discussion on these games, as you do play them.
but then that would overlap once the individual games have their own communities
You can always cross-post or tell people where to find the guides later.
If you search the modlog of lemmy.world with your name, you can see what the mod of /c/games said, what I can see is that it was taken as spam of old guides and/or not original content on that community, and they allow only a certain type of posts on that specific community.
There is no general modmail, so any mod can respond on Lemmy (at least yet), but you could DM the mods of the community individually to talk to them and see what is acceptable or not.
Remember that as it was the case on Reddit, there is the site rules and the community rules, sometimes some communities don’t allow certain things, or maybe they can think content can be spam or not original content.
Here you have multiple /c/games (or different names) communities on different instances, so if one doesn’t allow some types of post, another existing one can, or a new one can be created, or even you can create another /c/games.
It is true that here there are a lot of specific game communities that don’t exist yet but there is always the chance someone or yourself can create a community to fill what is missing (for example a /c/gameguides could be a new community for that type of content and be a hub for guides, specially for those games that doesn’t have a community yet).
Another thing, remember that the fact that you migrated from Reddit doesn’t mean that people will follow if you link to Lemmy even if you clarify that there is an updated version here, and content could be deleted from either Reddit or Lemmy side at any time, so even if it is as an alternative/backup I would consider having those guides on a third place (like docs that you mentioned, and link them somewhere on your posts).
Dislike: there is still no way to group communities into sub feeds, apart from subs, local, all. (and the work around some do of having multiple accounts seems silly to me)