We have hundreds of games in our database and that amount is continuously growing. That would mean a large amount of sub forums sorted by date of the last post in those forums.
It also means that instead of having the most recent posts on one page, We would have several forums on one page, each with one or perhaps two active treads.
It provides less overview and requires more navigation.
I think the advantage of using the proposed method would be that in a later stage it is easier to find all threads about a certain game.