Big games like Halo 4 are allowed more than one launch trailer. Following on from David Fincher's live-action effort, this gameplay trailer is all about showing off some slickly-edited footage, combat and cutscenes.
Basically, it looks great. More evidence of potential brilliance can be found in Matt's Halo 4 hands-on preview, though I'm still reserving judgement until I've gotten to grips with the new campaign. Here's hoping that there'll be one or two surprises left.