when you reach level 7777776, the next level is a Giant Master Chief boss from halo 3. use the energy sword you got from beating the tellytubbies to kill him.
beat him with any other weapon and you get an award (this means finish him off with another weapon)
there is a problem with the time setting of this game: it cant be in 2569 because the Human-Covenant War was going on at that time. if ne1 is wondering what that is, play more halo!