I like it, and it would stop people from putting in dozens of entities just to get more points

You don't get extra points for multiple entities.

The possibility for this to be done is there, but it could be tricky.

Really it's not all that hard. You put a super category in that can hold multiple entities. You then put all games with Mario into the super cat. When someone writes something about Mario they can click the Mario super cat and add all the games or they can open the super cat and choose the specific game. It would also cut down on scrollable lists if there were super categories.

The tricky part would lie in the coding, not in the visible implementation.

quote Avalith

The tricky part would lie in the coding, not in the visible implementation.

Not so hard, I gave you the outline. You make a table in the database that is the super cats and add a field into the existing game table that holds a value which assigns them into the super cats.

On the web side you pull the super cats and list the members of each super cat as a subset of them and anything not in a super cat is listed as a top level item just like the super cats.

Of course I don't know your actual database structure but I'm assuming that it's a robust SQL driven relational database because anything less would be a monster to manage. If that's the case then it wouldn't be so hard especially with the PHP front side.

Sure it'll be some work, but nothing worth doing is easy now is it?