Valve Software is known for handling their games with care, but with Portal 2, they've taken things a step further by throwing their hands into the games marketing.
In addition to the Aperture Science teasers (featuring the voice of JK Simmons as Aperture founder Cave Johnson) and a televised commercial, the publisher/developer also included a teaser trailer for Paramount Pictures/JJ Abrams' Super 8. The catch is: the trailer is interactive.
The player experiences the tease from the inside of a train seen crashing in various non-interactive trailers for the film, riding until it crashes then surviving to move around and examine the wreckage.
It's nothing compared to the game proper, but it's cool none the less. It might end up becoming a full game. You never know with Valve. Just look at the origins of Portal, which is available now on the PC, PS3 and Xbox 360.