Apparently there has been some speculation that the campaign for Halo 4 is short, due to a recent release of the game’s Achievements. Head of Halo lore Frank O’Connor and Spartan Ops game designer immediately came to the game’s defense on NeoGAF. They explained that even though the game has 8 missions, it doesn’t mean that the game is shorter time-wise than previous games.
Plus, don’t forget about the Spartan Ops missions, which–as mentioned back at E3–are co-op missions that cost NOTHING. In fact, Ellis says that the first season of the Spartan Ops missions will be longer than the main campaign of Halo 3: ODST alone. One mission will release a week for Spartan Ops mode for free. Free, people. I can’t emphasize that enough.
That’s plenty of Halo action for your buck. The moral of the story is not to judge a game by its Achievements. Now if a game has a massive single-player campaign with multiplayer tacked on and most of the Achievements are for multiplayer, judge away.