The new Portal 2 ad may not contain any in-game footage, but it sells the idea of playful, co-op puzzle solving quite nicely. Valve decided not to take the traditional route of hiring an ad agency to make the video for them. Instead, they built it in-house, and playtested it during production in the same way that they would with one of their games.
Valve's marketing VP Doug Lombardi spoke to MCV about the process of putting together the ad. He said that Valve decided to make it themselves because “No one knows the product better than the folks who made it,” adding that disastrous encounters with ad agencies over the years had shown them to be "almost worthless."
“With the Portal 2 ad, we playtested it and were able to make changes during production. With an agency, those types of tests are too often left to a post-mortem.”
Valve also made their own television ads for Left 4 Dead 2, you can watch the first one here , and the second one here . The 30 second Portal 2 video took Valve eight weeks to make. Portal 2 is due out in Aprill