It sounds like a good idea, but I'm not sure how it could be implemented - grouping games that are in the same series. Each game has its own ratings, and if games of the same series were grouped together, they would not be listed in order with all the other games. What I mean is, if in the same series, there was a 1 star game, a 2 star game, and a 3 star game, and someone clicked to sort the games list by rating, would it pluck games out of their series list, so that all the games were sorted correctly, or would you suddenly find a 3 star game halfway down the list?
Maybe members could have an additional category page in their My Stuff, that let them make a page that is similar to the front page of a game, but lets them list all the games in a series they wrote, and a blurb about what the series is about. Then, on any games front pages that are part of the series, they could link to that Series Page?