Because of the decision reached here, I have now committed to this proposal, for the reasons outlines below. Go Juan!
I've been holding my opinion on this for a long time, different arguments running around in my head. I think I've finally understood what I like and what I dislike about this suggestion.
Juan, I think your idea to put game-recommendations on their own SE sites is great. It really is. It would be a good home for these questions. Unlike other users here, I believe the SE engine is a decent engine for game recommendations, though of course there could be better engines.
And the best thing is, we could have an off-topic migration option from gaming to game-recs. That means that people who ask for game recommendations would not feel rejected when their questions get closed - and nobody likes getting their questions closed* - but instead, they'll get a much friendlier auto-migration to somewhere where their question is welcome.
So what's the problem? The problem is that it seems to me to be very bad for stackexchange in general. First of all, almost every site could use such a parallel SE for recommendations - [bike-rec], [camera-rec], even [library-rec] for stackoverflow.com itself. And worst, this fractures a community for (what I see as) no good reason; since the crowd for the normal site and the crowd for the recommendation site is the same. Same userbase, same expertise. Why split it? In my eyes, the people qualified and willing to answer questions about gaming problems are precisely the same people qualified and willing to answer questions about game recommendations.
[game-rec]s for me are the sort of questions that approach the same crowd as the other questions, most people occasionally want to see and they can also be clearly tagged as what they are (I believe we've had a success so far in tagging all game-rec questions appropriately) and ignored via that tag. I definitely feel they have a place here.
Two final points:
Juan's suggestion does have one interesting aspect, that it's actually a recommendation site paralleling more than one site - in particular, video games, tabletop games and role-playing games; but on the other hand the crowd for these three is not necessarily the same.
I've heard suggestions of some mythical 4th place that could be used for polls and opinions, thus providing a sort of built-in recommendation site for each of the websites. This is absolutely the best option in my opinion, and if it ever gets implemented I will most likely be strongly in favor of migrating all game-recs there.