On their official site, Bungie has teased what they called "Halo: Reach Super Secret Game Mode."
According to Bungie, in the new super secret game mode "some number of players will square off against some number of other players in what will undoubtedly be a rousing and highly competitive game of something we're not talking about yet!"
"Points awarded for doing all kinds of untold stuff!"
There, you have it. Now you know all what we know about Halo: Reach Super Secret Game Mode!