Google (NSDQ: GOOG) is about to start beta testing its in-game advertising program, which will initially involve the use of pre-roll and mid-roll inserts with gaming startup Bunchball Games, GigaOm reports. That initiative is expected to start this month. The second phase is set for December. Citing unidentified sources, GigaOm says that the second part of Google’s in-game ad efforts will revolve around an ad-supported, downloadable version of the PC game Psychonauts. This version will have 30-second pre- and mid-roll video ads as well. Google’s long-awaited “AdSense for Games” foray comes after its $23 million purchase of AdScape Media in February.