"Slayer." You read it in the announcer's voice, didn't you? It's a mode all Halo veterans are familiar with. It's a mode that has seen your most vicious killing sprees and caused your most tempered tantrums.
And it's a mode in the upcoming Halo 4's multiplayer, known as War Games. Since Bungie is no longer working on the series, passing the torch over to 343 Industries, I imagine there's some curiosity afloat as to just how addicted to rounds of multiplayer this next title will get you.