5: Halo 3
This trailer starts like a movie and really does a great job contrasting the innocence of the children at the beginning with the seriously barren land in the game.
4: COD: MW2
I honestly have no idea if this is a good trailer or not but I remember when I first saw it I couldn't contain my excitement for the then up-coming game so anytime I see this trailer now I get reminded of the first time
3: Fallout 3
Words cannot describe how good this trailer is at conveying the general chaos in this game world. As the camera zooms out from the radio and the sound truly makes you feel like the city is completely abandoned.
2: Dead Space
The trailer for a survival-horror game should leave you rummaging for your childhood blanky and a night light to plug in before you climb into bed. The effectiveness of the spooky lullaby playing over the few seconds of gruesome killing mixed in with the serene images of the ship creates an atmosphere unlike any seen before in a game trailer.
1: Deus Ex: Human Revolution
This game's trailer takes us on a brief walk through the protagonist's past, and in doing so shows off its spectacular gameplay. Although they are probably not using an in-game engine for most of the trailer you have to admit that its quality certainly good enough to be a movie.