Searching for new ways to expand its AdSense program, Google has just entered into a new market. Starting today the creators and the publishers of those little web-based games, also known as Flash games, will have the option to insert ads in the games.

As Google explained on its AdSense blog the ads could be inserted at the beginning or the end of a game and even when a level is finished.

By bringing the ads to the Flash games, Google could reach an impressive market: according to ComScore over 200 million Internet users are playing online games, at least once a week.

In fact, the idea of bringing ads in the online games is nothing new and Microsoft and Yahoo are already key players in this area. However, Google is the first to target Flash Games.

According to the media reports, the AdSense for Games program was developed by the team from Adscape Media, a small in-game advertising company, bought by Google in 2007.

For the moment the program is opened only to the publishers who have a minimum of 500,000 game plays and have 80% of their traffic from the U.S. or the U.K.

In 2006 Microsoft acquired n undisclosed sum for Massive Inc, a company that also serves in-game ads.

Earlier this year, Sony has signed a deal with IGA Worldwide to bring dynamic in-game advertising to its next-generation gaming platform, PlayStation 3.

Through this partnership, Sony hopes to get a share of the rapidly growing worldwide in-game advertising industry, which is expected to grow 1,150 percent to $971.3 million between 2006 and 2011, according to the Yankee Group.