Chronologically, the series starts out with the AI Buster Novel, Then the Sign Anime, followed by both the IMOQ Games and the Another Birth Novels. You can ignore XXXX as it is not technically canon, but rather an alternate to IMOQ and Another Birth. You can ignore Legend of the Twilight Bracelet (Nicknamed Dusk, by the fans) as well. It is written in a similar fashion to Link (It's more fan-fiction than canon). After that, you move on into the R00t Anime, and the G.U. Games. There are a whole bunch of series sprinkled about there, but these are the two big ones (I'd recommend the G.U. novels though. They're really good). Then quantum, and finally... *Shudders* Link.
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