How about a new skull for Halo 3 campaign?
It is a non-scoring skull called Mute Skull.
It turns off the Cortana and Gravemind ‘interruptions’ that happen during the campaign levels. The interruptions are fine if you’re playing for story, but when you’re playing for gameplay they get in the way.
Also the interruptions are fine two or three playthroughs in, but when you get to your tenth time through the game they basically become intrusive, disruptive, and pretentious time wasters.
Anyway I’m always having a good time playing through the levels and then one of these interruptions pops up and I’m like, ‘Oh no, please be over already!’ Fun meter diminishing! 
Anyway, just an idea. It may be that they are so integrated into the fabric of the level design it may break too much stuff.