The next set of "game master exception badges" is a little iffier as to whether they're necessary or not; they could be subsumed into other badges. I decided they were hinted at as being dealbreaker topics often enough that they could stand on their own.
My game uses an alternative approach to Wounds and Injuries. This could have been incorporated into the Combat badge, but I decided highly detailed or freeform wound systems are their own category.
My game uses different Monsters, or a different approach. Perhaps not as necessary a badge by itself, because few players object to GMs who use different monster rules behind the scenes. However, when I create negative exception badges, the "No Monsters" badge indicates that you don't use "monsters" at all, only humans and animals.
My game uses a different Skill system. Yesterday, I considered this part of the Class and Character exception badge, but I decided that skill systems is an enormous hot button and deserves its own badge.
I haven't worked out a good approach to the negative badge that doesn't obscure the image yet, so probably my next batch of badges will be genre badges.