How about a checkbox to allow and disallow certain hats?
It might be a little too exclusionary to REQUIRE a hat, but I like the "Hats Allowed" aspect!
In my opinion, I like the idea but just like there has been levels that does "Wear Santa, Party, Crown & Exp Hat" (just an example) you can't guarantee/know what others will wear.
I think if there's a way to know when a person clicks the level and can announce their hat in-chat for this type of category of the map it'll be better??
I know this is just asking for levels for 1 hat but this idea has potential for a lot of uses in PR2.
Anyways, just my 2 cent on it & hope it get looks at for a future update